ANIMALS. 139 



Atrypa pectinifera, J. de C. Sowerby. Morris, Catalogue, p. 120, 1843. 

 Terebratula pectinifera, /. de C. Sowerby. De Verneuil, Bull. Soc. G6q\. de 



France, 2"'^ serie, t. i, p. 27, 1844. 

 — — „ Geol. Rus., vol. i, p. 222, 1845. 



(?) — — „ Op. cit., vol. ii, p. 57, pi. viii, 



fig. 12 a, b. 

 (?) — CONCENTRICA, var., Fon Buck. Op. cit., vol. ii, pp. 54-5, pi. viii, fig. 11. 



— PECTINIFERA, J. de C. Sow. Keyserling, Petschora-Land, p. 238, 1846. 



Atrypa — ,, Tennant, Strat. List, p. 88, 1847. 



— — „ King, Catalogue, p. 8, 1848. 



— — „ Howse, Trans. T. N. F. C, vol. i, p. 253, 1848. 



— — „ Geinitz, Versteinerungen, pp. 11-12, pi. iv, figs. 



37-40, 1848. 



Diagnosis. — " Transversely obovate ; surface covered with concentric ciliated 

 fringes. "1 



This species, which has the valves " moderately and equally convex" (Sowerby), 

 has a striking resemblance to Cleiothyris Roissi/i (a larger shell) in its singular 

 pectinated or spinose lamellae of growth ; but it differs therefrom in having the 

 median sinus only slightly indicated. It has also some resemblance to Spirifera 

 expansa, Phillips, and some other carboniferous species. One of Mr. Sowerby's 

 figures correctly represents the spines projecting from, and forming part of, the 

 incremental lamellae : 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 Terebratula concentnca, Von Buch, be not a variety of Cleiothpis Boissp (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 PI. IV, 

 fig. 37, a, h, c), approximating in these respects to Cleiothyris Roissyi ; while others are 

 much narrower (vide fig. 38, a, b, 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 PI. 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 Terebratulida 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. Sovrerby, ' Mineral Conctology.' vol. vii, p. 14. 



