Pecten distortus Da Costa, 1778
COSTA, E. M. DA. 1778. Historia Naturalis Testaceorum Britanniae, or the British Conchology, containing the natural history of the shells of Great Britain and Ireland in English and French. London. Printed for the Author. [p. 148, pl. 10, figs. 3, 6]
«P. DISTORTUS. DISTORTED.
Tab. X. fig. 3. 6. P. parvus inaequivalvis, informis, striatus. Distortus. Tab. 10. fig. 3. 6.
P. minimus angustior, inaequalis fere & asper, sinu ad cardinem cylindraceo, creberrimi minutissimisque striis donatus. Lift. H. An. Angl. p. 186. tit. 31. tab. 5. fig. 31. Pecten minor ex croceo variegatus, asper & fere sinuosus & inaequalis, leviter & admodum crebro striatus. Lift. H. Conch, tab. 172. fig. 9. Twisted pectines of Stroma. Wallace Orkn. p. 43. 44.— Pecten minor alba contusa proteiformis. Petiv. Gaz. tab. 54. fig. 2.— Pusio. Writhen. Penn, Brit. Zool. No. 65, tab. 61. fig. 65. Concha testa aurita, striis circiter quadraginta. Lin. F. Suec. I. p. 384. No. 1345.— An Pusio. Lin. S.N. p. 1146. No. 200. Mus. Reg. p. 529. No. 113? The shell very thick and strong. The most general size is that of a large walnut, or about one and a half inch in length, and somewhat less in breadth. The whole shell is vastly irregular, but tends to a globose shape; however, it is always so writhen, crumpled, distorted, and seemingly bruised, that it appears always like a shell greatly hurt by accident, and hinder'd in its natural growth, for though constantly distorted, yet two shells hardly wear the same distortions. Both valves are convex, some greatly so, others less, and others so very little as to be near flattish. The outside of the flattish or upper shells is generally less uneven or warped than the other, for the bruisings or sinuosities are but slight on their upper or head part; on the lower they are larger and stronger, so that the margins are much depressed, and thrown out of their seeming natural position. The ribs or striae on this valve are always very visible, and generally not interrupted of broken by the warpings. This upper shell seems, when least diftorted, to be near flattish, or at most very shallow. The under valve is very deep or concave, and is the valve that suffers the greatest distortions or irregularities. The ribs or striae are always interrupted and misplaced. It is impossible to describe the various mishapings of this valve. The top or head part generally slopes very obliquely, and is prettily imprest with a small fine striated escallop; thence it rises into a very high irregular hump, and the impreffion there is generally quite lost or interrupted; and from thence it takes an almost perpendicular declivity; with many sinuosities or warpings, quite to the lower margins, and regains the ribs or striae, which are much thicker and stronger. The ribs are numerous, close fet, longitudinal and prominent, but very fine, or like mere threads, so that the shell appears only as thickly striated. The colours are mostly fullied white, pale dull violet, dull russety or sassrony; sometimes the upper or flattish shells are of a pale violet colour, or russety, and set with brownish transverse streaks, and the whitish ones are much mottled or variegated with red. The inside of the concave lower valves is white and smooth when alive, but russety, livid and dull, when dead or worn. The upper or flattish shells, when alive, have a strong pearly gloss. The lower margins, within, are finely notch'd or crenated from the outside ribs. The ears are large for the size of the shell, and nearly equal, when not lost in the irregularities or distortions; in that case they are greatly unequal, and one is sometimes even not very apparent. They are very sinuous, or bent to and fro, and are transversely striated. This odd species is found on some of our English shores, as in Yorkshire, at Scarborough and the mouth of the river Tees, the coasts of Dorsetshire, & c. Dr. Wallace got it on the shores of the Orkneys. At Stroma, a little island that lies in Pightland Firth, and in some places in Orkneys, where there went extraordinary cross and strong tides, he observed the pectens so twisted, and of such an irregular shape, that he was surprized to fee it. He adds "I cannot think the odd strange tumbling the tides make there can contribute any thing to that frame; yet, after all, I never fee them in any other place." OBS.—This kind is pretty frequently found fossïl in the chalk-pits of Kent and Surrey.» EMANUEL MENDES DA COSTA, 1778
|
E. M. da Costa, 1778, plate 10.
|