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The three genera, Canis, Vulpes, and Megalotis, make up the Family Canide (the dog family). The dog family has amongst its relations the Felide, or cat family (cats, tigers, lions, &c.), the Hyanide, or hyæna family, and the Mustelida, or weasel and badger family.

These families, together with the bear family and others, constitute the Order Carnivora, or flesh-eaters.

Of the numerous Orders, some of the best known are the Insectivora, or insect-eaters (ant-eaters, porcupines, &c.); the Marsupialia, or pouch-bearers (opossums, kangaroos, &c.); the Rodentia, or gnawers (rats, mice, &c.), which, together with the Carnivora, are grouped together, and form a Class, Mammalia, the members of which, it will be noticed, are all animals which suckle their young.

There are only four other Classes:-(i) Aves-feathered animals, which lay eggs and hatch them by the warmth of their own bodies (the birds); (ii) Reptilia-scaly-coated creatures which lay eggs, leaving them to be incubated either by the heat of the sun or that arising from decaying vegetable matter (snakes, lizards, turtles, &c.); (iii) Amphibia-slimy-skinned animals, which in their young stages are fish-like, living in water, and breathing through gills, but which subsequently acquire true lungs, and develop limbs suitable for locomotion on land (frogs, newts, &c.); (iv) Pisces-those scaly or naked animals, which live all their lives in water, and breathe through gills (the fishes). These five Classes collectively form the great sub-kingdom Vertebrata, and include all animals possessed of back-bones and true skeletons.

The sub-kingdom Vertebrata has been purposely chosen to illustrate the outlines of classification, because its members, if not numerically the greatest, are certainly the most conspicuous and best known to everybody, whereas the other sub-kingdoms, in their different ramifications, are more or less obscure to any but the scientific investigator.

Classifying "Ticks."

In order to determine the position of these small animals, it is necessary to consider another sub-kingdom called Arthropoda, which, in point of popular knowledge, comes nearest to the vertebrates.

The term is derived from two Greek words, arthron, a joint, and pous, a foot. The sub-kingdom comprises those animals with jointed limbs, having no back-bones or true skeletons; they have, however, an external skin composed of a hard, horny substance, which takes the place of the true skeleton seen in the vertebrates, and to the inner surface of which the muscles arc attached. This outer shell is made up of a series of segments or joints, and is spoken of as the "pseudo-skeleton.'

The sub-kingdom Arthropoda is naturally divided into four well-defined classes: (i) Insecta (true insects); (ii) Myriopoda (centipedes and millepedes); (iii) Arachnida (scorpions, spiders, and mites); and (iv) Crustacea (crayfish, crabs, and lobsters).

Many Arthropoda are spoken of as "insects," and for the purposes of economic and popular entomology, it is a suitable designation. The off-told story of the railway official who allowed a pet tortoise to travel free, because it was an "insect," illustrates one of the many curious uses to which the word is often put.

Strictly speaking, the word "insect" is only applied to the members of the class Insecta, those jointed-limbed animals which have the body divided.

into three distinct regions, viz. :-(1) the head, (2) the thorax or chest, and (3) the abdomen. The head bears two antennæ, whilst to the central portion or thorax are attached six legs, and nearly always one or two pairs of wings.

The second class, Myriopoda, is easily distinguished by the numerous legs of its members, of which they never have less than eight pairs.

The members of the third class, Crustacea, are nearly all aquatic animals, possessing two pairs of antennæ and the peculiar power of reproducing lost Îimbs.

The fourth and last class is the Arachnida, which comprises those modified insects having eight legs, and the body divided into only two distinct regions. They are wingless, and without antennæ, and like the Crustacea are able to grow new limbs where others have been broken off.

There are three orders of Arachnida, viz., (i) Scorpionida (the scorpions); (ii) Araneidea (the true spiders) and (iii) Acaridea (the mites).

The differences between these three groups are such as to render the distinguishing of the various members fairly easy. Thus the scorpions are at once recognised by their large mandibles and segmented bodies, having a curved claw at the extremity; the spiders, by having the abdomen unsegmented and very distinctly separated from the anterior portion of the body, to which it is attached by a small thin stalk; the mites, by having the head, thorax, and abdomen appearing all in one piece.

The order Acaridea is divided into about eight families the best known of which are the cheese-mites (Acarida), the Beetle-mites (Gamasida), the Plant-mites and "Red Spiders" (Trombidüda) and the Giant-mites or Ticks (Ixodide).

The tick family is made up of two genera: Ixodes,* the bush, cattle, and snake ticks; Argas, the fowl tick, &c.

To summarise briefly, we find that the ticks are gigantic mites related to the scorpions and spiders, and are modified insects belonging to the subkingdom of backboneless animals which possess jointed limbs.

Ticks.

Judging from the great numbers in which ticks occur in scrub country, many writers have raised the question as to whether they would not, from sheer necessity, be at times compelled to nourish themselves upon the juices of plants or flowers, deeming it incredible that all should find their way on to a beast.

The tea-trees (Kunzea and Leptospermum spp.), so common to our coastal districts, are called by many people, more especially that observant section of humanity-children-the "tick bush," and this bush is said to be more dangerous when in bloom, because at that time ticks are the most plentiful upon it. Whether the ticks frequent the blossoming plants for the sake of the honey, or to gain an easy access to the birds and animals attracted by the flowers, is an undecided question.

In my opinion the chances of the tick not reaching a host are equalised by their capability of living without food for very long periods, whilst the

*The genus Ixodes was divided into several sections, based upon anatomical differences by Koch. These divisions were accepted by Andrew Murray in his Economic Entomology (Aptera), and he created a new genus Ophiodes, in which he placed the snake-ticks. Mègnin in "Les Parasites" does not accept Koch's new genera, and for convenience they are not discussed here.

perpetuation of each species is provided for by the large number of progeny produced.*

The ticks of the genus Argas are readily distinguished from other members of the group. Ixodes and its numerous sections have the mouth parts terminal, that is, placed in front and in the natural position of the head; they carry also upon the back and immediately behind the head a shield or horny plate.

The Argasides have the mouth-parts situated upon the ventral surface of the body, almost between the first pair of legs, and the shield is entirely wanting.

The Fowl-tick (Argas sp.) †

Distribution.

Specimens of this fowl pest have been sent to the Department of Agriculture from Nyngan, Bourke, Louth, Deniliquin, and Sydney; and although I can find no reference to it occurring in any of the other colonies, nor any previous record of the presence of a fowl-infesting Argas in Australia, still, judging from the easy way in which the ticks might be carried about in fowl-coops, and its fairly wide distribution in New South Wales, there is every reason to believe that it is no uncommon poultry pest.‡

Life-history and Habits.

The life-history of the fowl-tick is essentially the same as that of other ticks. The eggs are, as a rule, laid in cracks and crevices and beneath the boards and rubbish with which fow-houses and fowl-runs usually abound. A correspondent of mine (Mr. J. D. Thompson) to whom I am indebted for many specimens of this pest, and much information concerning their attack and habits, says: "Sometimes the female tick deposits her eggs under the wings of the fowls and upon the thighs." From this it would seem that our local species lays its eggs in sheltered situations, or upon their hosts, and the latter habit, judging from what we know of the habits of other ticks, would appear to be more acquired than natural. These eggs are small and spherical, about the size of the hole made by driving an ordinary pin's point through a piece of paper. They are a translucent brown colour, and have been likened to small beads.

* The larva of the cattle-tick, according to recent investigations, does not mature at all until it has attached itself to its host, and it will live for "seventeen weeks" without any nourishment. In this connection the following note from the Bulletin of the Ento. Soc. of France (9th May, 1877) is also interesting:-"Dr. Fumouze showed his colleagues an Argas Persicus, which he had kept alive and without food since January, 1873. He observed that this specimen was the last of those exhibited during the meeting of the society on 11th November, 1874."

+ My friend, Mr. T. Whitelegge, the well-known naturalist of the Australian Museum, has since drawn my attention to a reference in "Natural Science," May, 1892, by Michael, to Argas Persicus, specimens of which were sent to him from Adelaide, South Australia. While our species tallies fairly well with descriptions and figures of A. Persicus without direct comparison of specimens it would be unwise to say that the two ticks are identical.

Mr. Thompson, of Deniliquin, in a recent letter (5th July, 1896) to me says, "I have known ticks to exist in Deniliquin for ten years past, but have had only three years' personal experience of them. I do not know of their existence anywhere else, but have heard that the same tick exists in Adelaide (S.A.) In this town it would be a difficult matter to find a poultry-keeper whose fowls are not troubled by these ticks." I may add that I have recently seen specimens of the Fowl-tick from Longreach, in Queensland.

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The larvæ or young ticks (fig. 1) which hatch from the eggs, are small white creatures with six long slender legs. In size they are a little larger than a pin's head; they are flat and ovo-triangular in shape, that is rounded behind and pointed in front. The mouth parts-which in the mites constitute the head-are, in this stage, terminal and distinctly seen from above. They are collectively spoken of as the rostrum, and consist of a dart or proboscis, furnished upon the lower surface with recurved hooks, and two

tw.

Fig. 1-Young tick or larva magnified and natural size.

Fig. 2-Enlarged sketch of Proboscis.

mandibles, placed upon the proboscis and capable of being withdrawn for a considerable portion of their length within the "head" and thrust out beyond the арех of the proboscis. These mandibles appear to me tubular, and to be furnished with organs for performing functions other than "biting" an entrance into the skin for the insertion of the rostrum. Each foot of the larva is furnished with two claws and a pulvillus or small cushion, which assist the tick to gain a firm foothold.

The full-grown ticks are tortoise-like, and, although generally of a brown colour, many of them are a bluish-grey. The edge or rim of the body is formed into a decided keel of light-yellow colour, and the skin or tegument is much roughened and pitted in many places. They have eight legs-one pair more than the young-which are of a transparent white colour. The feet are furnished with two claws, but the well-developed cushions seen upon the larvæ are absent.

The ticks are of an oblong-ovate shape, being broader behind than in front. In length they range between one-fourth and one-third of an inch, whilst I have seen some exceptionally large specimens quite half an inch long. (See fig. 3.)

The mouth parts and palpi are situated upon the lower surface of the body, a little in advance of the first pair of legs. (See fig. 4.)

It has been observed that the bush, cattle, and snake-ticks attach themselves in a "quasi permanent" manner to their hosts: that is, once they gain a footing they remain upon their hosts until they are mature, the females only dropping off when ready to start laying eggs. This is not the case, however, with the fowl-ticks, which, even when larvæ, feed only at night,

hiding away in some dark corner during the day-time. I have noticed that when these ticks are exposed to the daylight they are restless until they find a dark crack to crawl into, and although, apparently, they have no eyes, they are capable of distinguishing the direction of light. It appears to me quite

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certain that the habit of the ticks of feeding only at night has been adopted for protection. Such conspicuous parasites would not long escape the viligant eye of a fowl in daylight.

A point of interest about these ticks is their power of living for considerable periods without nourishment. Mr. Thompson sent me specimens said to have been kept in a match-box five or six weeks, many of which are now-one month later-alive, and in apparently the same condition as when they arrived. My correspondent also adds that he has kept them in this condition during the cool weather for three and four months.

Argas reflexus, a species which attacks doves and pigeons in England and upon the Continent, was kept by Professor Hermann alive without food for eight months.*

On every occasion that the fowl-ticks described in this paper have been referred to me they were accompanied by statements to the effect that they were the cause of great mortality amongst the affected poultry, and more especially fowls newly introduced to infested roosts. These latter generally succumbed to the attacks of the ticks in four or five weeks, but many of the other fowls become "tick-proof." One correspondent says that they cause a "fever," from which the fowls soon die.

From the evidence at my disposal it would appear that the ticks are the cause of a general weakness, which strongly manifests itself in the legs, the use of which is lost before death. As yet, one cannot say whether the sickness and subsequent death are due to exhaustion, consequent upon great loss of blood, or to a "fever" or poison" carried by the tick in the manner that Ixodes bovis communicates Texas fever. Dr. Francis leans towards this view, as will be seen upon reference to the remarks made in his paper, reprinted

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*P. 138, Les Parasites par P. Mégnin.

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