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every sweep; and, slowly congregating in their ascent, continued thickening in numbers and lessening in the distance, till at length, “parvis componere magna” (to compare great things to small], they assumed exactly the appearance of a swarm of Aies. At last they vanished to the westward; but whither they pursued their route I cannot tell, though I suppose that they retired straight to roost among the osier beds beside the Thames.

Mr. Selby observes of the bank martin, that he is not aware whether they ever congregate in the autumn, like the other species, previous to their migration. They certainly do congregate, and in tens of thousands, the flocks sometimes alighting on the ground; and generally passing the night in large beds of reeds or osiers.

Last of all the summer birds of passage, arrived the night-jar (Nychtichelidon europæ`us), the loud burre of which was first heard here on May 15. This is early; but they may possibly have arrived a little before, as they are not common in this immediate neighbourhood, though a few always make their appearance. They are plentiful in the Coombe district; and I have seen them in Dulwich woods, and upon Penge Common, within five miles of London.*

To conclude: I did not, this season, observe any ring ousels, nor pied flycatchers + (M. luctuosa). The former usually make their appearance here about the middle of April; the latter in the early part of that month, being one of the first summer birds of passage. Query, Should this species, and albicollis, range in the same minimum division as M. Grisola ?

The noting down the arrivals of our small summer visitants has become a subject rather destitute of novelty; but it is still interesting to compare observations made in different parts of the kingdom; and, with this view, I have been induced to offer the present communication. Tooting, Surrey, May 21, 1834.

EDWARD BLYTH. * [The nightjar was heard at Stanley Green on May 15.: it had probably just arrived. It has no regular habitat here, as far as I am informed. The bird arrived seems to be a solitary individual; at least I have not seen its mate.

It made a fearful clatter on the 15th and 17th, from 7 o'clock in the evening until midnight. It was silent on the 16th, in the evening of which day it was hovering about the garden. (W. B. Clarke, in a communication dated Stanley Green, May 19. 1834.) See, in p. 156, other facts from Mr. Clarke, on the habits and time of migration of the fern owl.]

+ Since writing the above, a field Aycatcher's nest has been discovered in the identical hole (of a large ivied poplar), in which three successive nests of this bird were destroyed last year : see the Field Naturalist's Magazine for March 1834, p. 117. This is a most remarkable instance of persevering attachment to a particular location, for I have no doubt whatever that these nests were all built by the same pair. - E. B. May 30. 1834.

In Taylor's London and Edinburgh Philosophical Magazine and Journal of Science, the Number for May, 1834, there is published an interesting communication, entitled “ Notice of the arrival of twenty-six summer birds of passage in the neighbourhood of Carlisle, during the spring of 1833.” —- J. D.

A Cuckoo pursued by a Meadow Pipit. - Happening to hear, when passing over Mitcham Common, a few days since, the full melodious note which the cuckoo often utters on the wing, I looked around, and soon perceived a meadow pipit (A'nthus pratensis) chasing a cuckoo through the air, at a considerable height from the ground; following it at least a couple of hundred yards, and attacking it repeatedly, with wonderful spirit, till at length it seemed no longer able to keep up. On returning to its nest, it probably found a new object for its affections. - E. Blyth.

Art. VII. Illustrations in British Zoology. By George John

STON, M.D., Fellow of the Royal College of Surgeons of Edinburgh.

21. PLEUROBRA'NCHUS PLU'MULA ( fig. 46.)

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a, A view of the back, when the animal is in progression. bbb, Three views of the ventral

surface cc, Two views of the shell. All of the natural size.

Synonymes. - Búlla plùmula Mont. Test. Brit. p. 214. t. 15. f. 9. (the shell), Turt. Br. Faun. p. 168., Turt. Conch. Dict. p. 25.; Pleurobránchus plùmula Flem. Brit. Anim. p. 291.; Berthélla poròsa Blainv. Malacolog. p. 470. t. 43. f. 1.

DESCRIPTION. Body oval, convex dorsally, of a uniform cream-yellow colour. Cloak smooth, reticulated with minute clear spots, so as to appear almost porous, like a piece of fine

sponge; the margin thickish, plain, undulate, free, and sufficiently broad to conceal the foot when at rest. Tentacula arising between the cloak and veil, superior, two, cylindrical, short, formed of a membrane folded into a tube slit along one side. Eyes two, small, black; one at the superior base of each tentaculum. Veil above the mouth broad, somewhat triangular, produced at the upper and outer angles, which are folded. Mouth shortly proboscidiform. Space between the cloak and foot smooth, deep. Orifice of the generative organs on the right side, placed very forward, tubercle-like. Branchia arising immediately behind it, single, naked, plume-like, and pectinated; the posterior half free. Foot oval, tapering posteriorly when in a state of extension, and projecting beyond the cloak ; the margins undulate, plain. Shell concealed in the substance of the cloak, dorsal, ovate-oblong, depressed, with a minute spire at one end; brownish, thin, pellucid; strongly wrinkled concentrically, and marked with a slight fossa from the apex to the opposite angle, Length 6 lines, breadth 3} lin. I am unable to describe the internal organisation of this interesting mollusc; but it may be permitted me to direct the student's attention to the wonderful structure of its oral organs, which I could not (although not unfamiliar with analogous structures in congenerous species) view without a feeling of indescribable pleasure and amazement: and, to the lovers of the microscope, I am satisfied that no object can afford a more gratifying display. Within the soft parts of the mouth there lie two thin oval plates, one on each side, reticulated in an inconceivably minute and regular manner, after the fashion of the compound eyes of many insects; the meshes being diamond-shaped, and set with a small obtuse process at each angle. Between these plates (which, I presume, are a modification of the maxillae or jaws) the tongue is situated : a broad membrane, folded at the sides, and armed with innumerable little spines or teeth, arranged in close-set transverse series, parting from a longitudinal medial line. The tongue is of a square shape, rounded at the lower end; to which is appended an inversely heart-shaped piece of similar structure and appearance: the whole fitted to rasp down the vegetable matter on which the animal feeds. The cloak is fleshy, but not fibrous; and, in its composition, includes many small crystalline spicula of carbonate of lime, which are also to be found in the foot and branchia. These spicula are colourless, short, cylindrical, and rounded at both ends; and they seem to have no determinate arrangement. I have found similar spicula, but larger and more abundantly, in the tegumentary system of the Döris.

Our figures exhibit the animal of its natural size; and were taken from specimens found, between tide-marks, in Berwick Bay. Like the land slug, it progresses by obscure undulatory motions of the foot; but it justly claims the “bad preeminence” of being superior in sluggishness and tardiness.

The specific name of Blainville is unjustifiable; and no authority can warrant our adoption of it. Montagu (the discoverer of the species) called it Búlla plâmula "; and, although the generic name must be altered to suit the progress of science, his specific name is sacred, and is beyond the changeful caprice of any systematist. Blainville has done some further wrong to Montagu, in ascribing even the discovery of the mollusc to Donovan; whose name, I may observe, is often substituted for that of the former naturalist by foreign authors, and by some careless translators in our own country. Berwick upon Tweed, Jan. 3. 1834.

ART. VIII. Description of some nondescript and rare British Species of Shells. By WILLIAM TURTon, Esq. M.D. &c.

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Testa rhombea, inferne rotundata, pellucida, albidū vittis longitudinalibus interruptis pallide violaceis; margine antico incurvato.

Shell rhombic, rounded below, transparent, whitish, with pale, violet, longitudinal, interrupted stripes; the anterior margin incurved. Nearly an inch long, and full half an inch broad; extremely thin and brittle; obliquely truncate at the top, with a few pale violet spots below; hollowed out at the front margin in a slight crescent-shaped form.

This most interesting addition to our native stock was taken alive at Scarborough; and is in the cabinet of Mr. Bean, who obligingly sent the accurate drawing from which the figure was taken. He has given it the specific name of Travisii, after Mr. Travis, well known for his valuable communications to Pennant. In its outline, it differs from any of those figured by Sowerby, or described by Lamarck.

My'TILUs striatulus Linn. Mant. p. 548., Schraet. Einl. iii. p. 449. t. 9. fig. 16., Gmel. p. 3358.

Testa subtrigona, striis longitudinalibus elevatis crenulatis.

Shell somewhat triangular, with raised, longitudinal, slightly crenate striae.

Length three quarters of an inch, and hardly as much in breadth; semitransparent, dark horn-colour, with a few paler zones; marked with nume

* He subsequently constituted with it a new genus, which he called Lamellària, a name preoccupied in botany.

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rous slight longitudinal ribs, which are crossed by transverse depressed lines, giving them a granulated surface: the front margin a little incurved; the hinge margin angular. This beautiful species, which has long been a desideratum to the science, was taken in abundance, by Mr. Bean, on some floating wood at Scarborough, who kindly sent us some specimens. [See, in connection, the communication in p. 353.] PLEURO'ToMA TREveLLIANUM [Turton]. Testa ovato-fusiforme; ansractibus 6–7, striis numerosissimis, apice deplanatis. Shell oval-fusiform; with 6 or 7 volutions, very closely striate, and flattened at their tops. This new and very distinct species was found, by Mr. Bean, abundantly at Scarborough. It is so extremely like the Mürex turricula of Montagu, as to be hardly distinguished, except by the following marks: — 1st, The outline is of a more inflated cast; 2dly, the striae are twice as numerous; 3dly, and the distinct notch at the upper angle of the outer lip fixes its genus. In this genus we have also the Mürex grácilis, M. septangularis, and M. linearis of Montagu, and the M. Chórdula of our Conchological Dictionary; a pair of which, collected by ourselves, are now in the cabinet of Mr. Clark. The M. purpūreus of Montagu has sometimes this pleurotomatic notch.

FU’s Us FENESTRATUs [Turton].

Testa oblongo-fusiformi, alba, costis numerosis longitudinalibus striis transversis reticulatis; antractibus octo, tumidis; cauda producta, sinistrorsum curva; apice papillari; fauce albo laevigato.

Shell oblong-fusiform, white, with numerous longitudinal ribs, which are reticulate by transverse striae : volutions eight, swollen; the tail produced, a little turned to the left; mouth white, smooth; the tip papillary.

Length, 14 in. ; breadth, five eighths of an inch. In its outline it much resembles the Fusus corneus; but the volutions are much more rounded and deeply divided, and the tail is not so much elongated; the reticulations are rather coarse, and slightly granular at the points of junction; the colour is also of a much clearer ivory white.

A pair of these were dredged up at Cork; one of which

was sent to us by Mr. Humphries, and is now in the cabinet of Mr. Clark.

FU'sus Norwegicus [Turton], Strömbus norwegicus Chamn. Conch. x. t. 157. fig. 197, 198. Testa laevi, eburnea; ansractibus planiusculis; ultimo ventricoso; labro dilatato, intus laevigato. Shell quite smooth, ivory white; volutions rather flat, the lower one ventricose ; outer lip much dilated, and smooth on the inner margin. Length 5 in., and about 2 in. broad; with six volutions, the last of which is much enlarged; of an ivory whiteness, with a slight ferruginous stain; aperture very large, twice as long as the rest of the shell, pure white

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