170 SUPPLEMENT TO THE BRITISH 



internal cast of Ter. ornithocephala ." but this may be a mistake. In 1850 I had only 

 seen the internal cast figured by Sowerby, of which I now append a careful drawing 

 made from the original specimen (Sup., PI. XXII, fig. 6) now in the British Museum. 

 Since that period I have been able to examine a large number of specimens obtained by 

 Mr. J. E Walker from the Supra-coralline beds or red ferruginous rock at Abbotsbury 

 in Dorsetshire. After careful comparison of these (Sup., PI. XXII, figs. 3, 4) with 

 examples of W. ornithocephala (Sup., PL XXII, fig. 1), I was able to detect very little 

 difference between many of the specimens. Some of them, however, presented a small 

 longitudinal depression at the umbone, not observable in W. ornithocephala, and the 

 shell is likewise less pinched in laterally and anteriorly, the smaller valve flatter and the 

 beak more incurved. 



Mr. Deslongchamps admits that he was mistaken when he supposed this species to 

 be the internal cast of W. cornuta, to which it bears no resemblance. He observes, 

 moreover, that it is a form very abundant in the Oxford Clay of the East of France, also 

 in the Argile de Dives, Normandy, and that he had always considered it as a variety of 

 T. bucculenta. He adds that in d'Orbigny's collection, in the Museum of the Jardin des 

 Plantes, this species also bears the name of T. Royeriana, and is mixed up with specimens 

 of W. umbonella. 



The Abbotsbury examples of W. lampas are of a brown ochreous colour, due to the 

 ferruginous nature of the matrix. Sowerby's figure is also of a red-brown colour, and 

 some information may be obtained from the colouring of the plates with regard to the 

 rocks from which that author's specimens were derived. Mr. J. E. Walker informs me 

 that the Abbotsbury specimens come from near the spot whence the internal cast figured 

 by Sowerby was obtained. According to Mr. D. Stephens W. ornithocephala first 

 occurs in the Inferior Oolite ; but it is a most abundant and characteristic fossil of the 

 Puller's Earth. Wald. lagenalis abounds in the Cornbrash ; W. umbonella, a variety of 

 ornithocephala, in the Kelloway Rock ; and W. lampas in the Supra-coralline bed : 

 these are all closely allied forms, perhaps descended from a common ancestor. 



149. Waldheimia Cadomensis, E. Bed., sp. Dav., Ool. Mon., PI. VII, figs. 6 and 



9 ; and Sup., PI. XXII, fig. 9, and 

 PI. XXIV, figs. 14, 15. 



Terebratula ornithocephala, Dav. (pars). Ool. Mon., pi. vii, figs. 6 and 9, 1851. 

 — (Wald.) Cadomensis, JE. Desl. Description des Couches du Systeme 



Oolitique Inferieur du Calvados ; 

 Bull. Soc. Linn, de Normandie, 

 vol. ii, pi. iv, figs. 3, 4, 1857. 



Shell elongated oval, widest posteriorly, tapering anteriorly, straight in front ; valves 

 nearly equally deep, very convex, especially at the umbo of the dorsal valve, sometimes 



