ANIMALS. 139 
ATRYPA PECTINIFERA, J. de C. Sowerby. Morris, Catalogue, p. 120, 1843. 
TEREBRATULA PECTINIFERA, J. de C. Sowerby. De Verneuil, Bull. Soc. Géol. de 
France, 2™ série, t. i, p. 27, 1844. 
pies pal nh Geol. Rus., vol. i, p. 222, 1845. 
(?) — — a Ope Cites avOls t,o p. 07, olen vin 
: fig. 12a, 6. 
® — CONCENTRICA, var., Von Buch. Op. cit., vol. ii, pp. 54-5, pl. viii, fig. 11. 
— PECTINIFERA, J. de C. Sow. Keyserling, Petschora-Land, p. 238, 1846. 
ATRYPA = a Tennant, Strat. List, p. 88, 1847. 
_— — 6 King, Catalogue, p. 8, 1848. 
= = i Howse, Trans. T. N. F. C., vol. i, p. 253, 1848. 
— — Dp Geinitz, Versteinerungen, pp. 11-12, pl. iv, figs. 
37-40, 1848. 
Diagnosis.—© Transversely obovate; surface covered with concentric ciliated 
fringes.” 
This species, which has the valves “ moderately and equally convex” (Sowerby), 
has a strikmg resemblance to Cleiothyris Roissy (a larger shell) in its singular 
pectinated or spinose lamellze of growth; but it differs therefrom in having the 
median sinus only slightly indicated. It has also some resemblance to Spirifera 
eapansa, Phillips, and some other carboniferous species. One of Mr. Sowerby’s 
figures correctly represents the spines projecting from, and forming part of, the 
incremental lamelle: they are in some instances nearly a quarter of an inch in 
length. If the Russian Permian shell, which M. de Verneuil considers a variety 
of Zerebratula concentrica, Von Buch, be not a variety of Clesothyris Roissyc (which 
is also a Permian shell, in Russia), I should have very little hesitation in referring 
it to the present species; although none of my specimens display the sinus so strongly 
marked as it does. 
Cleiothyris pectinifera appears to have been a more variable shell in Germany than 
in England, as all my British specimens have a remarkably striking similarity to each 
other ; whereas those occurring in Germany, judging of the figures given by Dr. 
Geinitz, are extremely variable in form,—some being wide and flattened (vide Pl. IV, 
fig. 37, a, 6,¢), approximating in these respects to Clezothyris Roissy: ; while others are 
much narrower (vide fig. 38, a, 6, c) than any that have occurred to me in England. 
The internal structure, which I consider diagnostic of the genus, is pretty 
correctly represented in Pl. X, figs. 8 and 9; and so is the pectinated character of the 
spiral processes in fig. 10 of the same plate. I may also refer to one of Mr. Sowerby’s 
figures, which, besides displaying the peculiarity last noticed, exhibits the homologues 
of the free portions of the crura of the loop in Zerebratulide similarly pectinated. The 
apparent union of these parts, in the figure under notice, has already been alluded to. 
(Vide ante, pp. 122-3.) 
1 J. de C. Sowerby, ‘ Mineral Conchology.’ vol. vii, p. 14. 
