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LYNCEUS MACROURUS, Müll., is much rarer than the preceding species, to which it bears a striking general resemblance. Buttermere, Derwentwater, and Blea Tarn (Langdale) are the only localities in the Lake district where I have met with it. It seems to be a lowland rather than an alpine species.

LYNCEUS QUADRANGULARIS, Müll., is still more decidedly of lowland proclivities, being quite one of the rarer species in mountainous districts, but almost the cominonest of British Lyncei in the plains. I have taken it, however, sparingly in Grasmere, Easdale Tarn, Derwentwater, Blea Tarn (Langdale), and in pools in Ennerdale. Its place in the waters of the lowlands seems in mountain regions to be usurped by the following species :

LYNCEUS ELONGATUS (G. O. Sars)—Fig. 8—which may be looked upon as the form most characteristic of mountain lakes, its strongholds being bleak, elevated sheets of water, such as Stickle, Angle, and Sprinkling Tarns, while at low elevations, and especially in small pools, it is much scarcer. In the lowland and southern districts of England it is not at all met with. When living in high, bleak tarns, it is often of a very deep, opaque brown colour, verging on blackness, and sometimes appears to be almost the only animal inhabitant of the water; but in lower and more sheltered situations it to a great extent loses its deep colouring. A very remarkable peculiarity of L. clongatus is that the carapace, though normally consisting of two valves, like all the rest of the genus, is very often found to be made up of two or three pairs of valves superimposed one on another. This condition is seen in the specimen represented at Fig. 8 of our plate, the six layers of carapace being plainly indicated by the minute tooth at the lower posterior angle of each. In this condition the edges of the several valves occupy very various positions. Sometimes all three (and I have never seen more than three) are pretty close together, as in the figure; at other times the edge of the uppermost comes nearly in the middle of the animal. It is remarkable, too, that the several coats do not separate in the process of exuviation, for the sloughs, which are often taken in great numbers along with the living animals, constantly show the several valves in union just as when alive. I cannot yet say whether the young are born in the multivalvular state, or whether it is a result of growth, but in every copious gathering of L. elongatus many specimens in this condition are sure to occur, and in some they form almost the greater part of the whole. This is the more interesting when considered in relation to a very curious species of the same family, Monospilus tenuirostris, one striking character of which consists in a somewhat similar but much more pronounced multi

plication of valves; and the qnestion suggests itself—do wa, in the case of L. elongatus, see a species which is undergoings gradual transformation in the same direction ?

L. elongatus occurs in all the gatherings which I hate made in the Lake district, and is frequent also in sime situations throughout the north of England and Scotland.

LYNCEUS COSTATUS (G. 0. Sars), seems to be a tolerabt common inhabitant of lakes and clear water in moderate as. tudes, but is seldom found in more elerated and exposed situations. Buttermere and Derwentwater are the only tv, localities in our Lake district where I have met with it.

LYXCUS GUTATTTS (G. 0. Sars).- Well marked forms d this species are undoubtedly very distinct from the foregoing, but I am disposed to doubt whether the differences ought ou to be regarded as varietal rather than specific. It is not urcommon in similar situations, ascending, however, to greater altitudes, and ranging from the sea-level to a height of 1 feet (11ngle Tarn). The following are the lakes in which I have met with it: Buttermere, Thirlmere, Easdale, Languale. Angle and Sty Head Tarns.

LYNCETS TESTTDINARIUS, Fischer, is a widely distributei and very well marked species, and appears to haunt inditterently water of all degrees of exposure and elevation. It occurs in my gatherings from Buttermere, Langdale, Angle and Sy Head Tarns, and from pools on Eskhause, at an elevation of about 2000 feet.

LYNCEUS EXIGUUS (Lilljeborg).—A very small, but well marked species, occurring in almost all the waters of the lake districts, but more commonly in those of considerable altitude. I find it in Buttermere, Thirlmere, Derwentwater, Easdale, Langdale, Sprinkling, Sty Head, Stickle, Angle and Floutern Tarns, and in the river Brathay, below Skelwith Bridge.

LYNCEUS TRUNCATUS, Müller, is a common species in the low country, and at moderate degrees of elevation in the lake district, but is not so frequent in the higher mountain tarns, the greatest height at which I have found it being 915 feet (Easdale Tarn). It occurs also in Windermere, Grasmere, Rydalwater, Derwentwater, Langdale, and Blea Tarns; in pools in Ennerdale, and in the River Brathay.

LINCEUS UNCINATUS (Baird).—This species is at once known by the upturned extremity of the rostrum and strongly toothed infero-posteal angle. Buttermere is the only one of the lakes in which I have found it.

LYNCECS NANUS (Baird), the smallest of the British Lyucei, occurs at all altitudes. I have noticed it in Buttermere, in Floutern, Blea, Sprinkling, and Sty Head Tarns, and in pools on Eskhause and Honister Pass.

LYNCEUS GLOBOSUS (Baird). (Fig 7.)–One of the finest, and by no means one of the commonest of the British species, living always in clear water, where there is abundance of vegetation, and mostly in situations of no great altitude. In the lake district it inhabits Windermere, Grasmere, and pools in Ennerdale. From a specimen taken in the latter place our figure has been drawn. The shell, when closely examined, after the internal parts of the animal have been removed, is seen to be regularly reticulated throughout, but on the ventral margin the reticulations partially coalesce, so as to form concentric furrows. In the living state these markings are a good deal obscured, and give rise to an appearance of dotting or scaliness which does not really exist.

LYNCECS BARBATUS, nov. sp. (Figs. 1, 2).-Carapace subsemicircular; dorsal margin boldly arched from the posterosuperior angle to the extremity of the rostrum, which is long, slender, and acutely pointed, and projects beyond the ventral margin ; ventral margin gently convex, fringed with spiniform hairs which commence about the middle, and gradually increase in length to the posterior extremity, where they end abruptly ; posterior margin slightly angular above, rounded off below; anterior antennæ slender, about half the length of the rostrum; abdomen broad and short, superior margin deeply excavated, superior posteal angle produced and obtusely rounded, armed with about nine long and nearly equal spines, terminal claws slender and bearing a single small spine at the base; eye-spot situated nearer to the eye than to the extremity of the rostrum, and about half its size; shell devoid of reticulation or striation, but slightly waved round the margin, especially on the dorsum. Length one fifty-fifth of an inch.

This is a very distinct, and apparently a rare species. I have seen only four specimens, three of which were taken in Buttermere, and one in a pool in Ennerdale.

LYNCEUS SPHERICUS, Müller-(Fig. 6)—is found everywhere, from the smallest road-side pool to the most elevated mountain tarns, but is most abundant in somewhat foul and stagnant water.

Var. FAVOSA (Figs. 3—5).—Closely allied to the last, and almost exactly similar in shape, except that the rostrum is perhaps somewhat longer and more slender. The markings of the carapace are, however, entirely different, consisting of very deep and conspicuous irregularly angular excavations, which are restricted to the head and the inferior and posterior portions of the carapace. The margins of the valves are always entirely free from these markings, but their distribution over the other portions is somewhat variable, and the parts not thus marked are quite devoid of reticulation, or any perceptible structure, as represented in Fig. 5. In the typical form of L. sphericus, on the other hand, the surface is regularly, but faintly reticulated, as shown in Fig. 6. This is most plairly seen in young specimens, but in older examples is often visible on the margins only, while the margins of the valves in the variety farosus are always, as has been said, quite destitute a sculpture. Length one fifty-eighth of an inch.

This form occurred plentifully in some small peaty pools ci Eskhause, at an elevation of about 2000 feet. The peculiarities of shell sculpture lead me to suspect that it may be a distina species, though it must be confessed that in other respecta there is little or nothing to distinguish it from L. sphericus.

EURYCERCUS LAMELLATUS (Müller) is common in all the loro lying lakes, but does not apparently inhabit those of great altitude. The only tarns in which I have found it being Langdale (3-10 feet) and Easdale (915 feet).

EXPLANATION OF I'LATE.
Fig. 1.--Lynceus barbatus, nov. sp., female, x 84.
Fig. 2.-Abdomen of the same, x 210.
Fig. 3.-Lynceus sphæricus, var. farosa, female, x 8i.
Fig. 4.-Abdomen of the same, x 300.
Fig. 5.—Exuvium of left valve, showing sculpture, X 84.
Fig. 6.—Marginal reticulations of Lynccus sphæricus, x 210.
Fig. 7.Lynceus globosus, female, x 50.

Fig. 8.Lynceus elongatus, female, multivalvular form, x 50.

Fig. 9.Daphnia Jardinii, female, x 25.
Fig. 10.-Abdomen of the same, x 40.

THE PHILOSOPHICAL INSTRUMENTS IN THE

PARIS EXHIBITION.

BY C. R. WELD. Amidst the vast gathering of products of human industry and invention, which attracted millions of visitors from all countries to the French metropolis this year, the objects classed under the head of Philosophical Instruments hold very high rank. For it is, to a great extent, by the agency of these instruments that the present generation enjoys comforts and luxuries wholly unknown to the early inhabitants of our globe.

While contemplating with feelings of wonder and awe the pyramids of Egypt, we cannot but remember that though they are stupendous monuments of the former rulers of that country, they are also monuments of slavery and drudgery, for by brute force were they heaped up, thousands of toilers and long years being required to do that which now, by the aid of machinery, could be effected in a few months. When the inhabitants of a country are condemned to unceasing labour, progress for the race is impossible. “How,” remarks Solomon, thinking probably of the slavery of the nations around him, “ shall he that toileth all day long have knowledge,” and assuredly the more that we can make machinery perform offices of manual labour, the more will man be raised in the scale of civilization, provided always, that with the leisure thus afforded him, suitable education is provided. For, just in proportion as the exertions of those who toil are aided and systematized by the employment of force-evolving machines, will there result surplus wealth, more and more leisure for all, an educated class spreading wider and lower; in a word, all that is man's proper destiny-progression in happiness.

How greatly machinery is indebted for its perfection to philosophical instruments is well known. Mr. Fairbairn, the eninent engineer, says that when he first went to Manchester, the whole of the machinery required for the mills in Lancashire was made by hand. Now tools, which may be almost regarded as philosophical instruments, so exquisitely accurate and highly scientific is their construction, are employed for this work. The high character of modern British machinery is due to the great pains bestowed on the tools used for its fabrication, a large proportion of which are made by Mr. Whitworth. With the wonderful measuring machine invented by this gentleman, demonstrating the one-millionth of an inch,* and his true plane,

* Mr. Whitworth has presented one of these really marvellous machines, and three of his true planes to the South Kensington Museum.

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