214 SUPPLEMENT TO THE BRITISH 



218. Var. SociaZis, Phillips. Sup., PI. XXVIII, figs. 8 to 11. 



Terebratula socialis, Phillips. Geol. of Yorkshire, part i, p. 112, pi. vi, fig. 8, 1829. 



Shell somewhat transverely oval, wider than long. Valves very convex, especially 

 the dorsal one, and forming in profile a regular convex curve from the extremity of the 

 umbo to the frontal margin. A well-defined and rather broad mesial fold gradually 

 rises at about half the length of the valve from the umbo. The ventral valve is divided 

 by a wide shallow sinus commencing at about the middle of the valve, and extending 

 to the serrated frontal margin of the opposite valve. Beak much incurved. Surface of 

 each valve marked with a variable number of rather strong, angular ribs ; from sixteen to 

 eighteen in each valve, of which about five occupy the fold and sinus. 

 Length 8, width 10, depth 7 lines. 



Obs. — Phillips's figure denotes a shell exceeding in size the usually small var. Smithii 

 from the Pullers' Earth. The longitudinal, regular, convex curve of the dorsal valve, 

 and its strong ribs, distinguish it from the other varieties of this variable species. 

 This is the shell represented by Phillips's figure. Many examples can be obtained from 

 the Kelloway Rock of Scarborough. We should, in our discrimination of a species or 

 variety, bear in mind the characters assigned to it by its proposer. Along with the 

 var. socialis, in the same rock and locality, are found specimens closely resembling 

 the typical Rh. varians, which, as we have already stated, may be the shell so named by 

 Schlotheim. Some specimens approach, likewise, to the variety that occurs in the Oxford 

 Clay, near Scarborough, specimens of which may be seen in the York Museum. 



219. Var. spathica, Lamarck? Sup., PI. XXVIII, figs. 5, 6, 7. 



Terebratula spathica, Lamarck (pars). Anim. sans Vert., torn, vi, p. 256, 1819; 



and Dav., Exam, of Lamarck's Species 

 of Fossil Terebratulae, Annals and Mag. 

 Nat. Hist., 2nd ser., vol. v, 1850. 

 Rhynchonella — Oppel. Die Jura-Formation, p. 576, 1857. 



— — E. Desl. Bull, de la Soc. Linn, de Normandie, torn, iv, 



p. 246, 1859 ; and Mem. Soc. Linn, de Nor- 

 mandie, vol. xi, 1859. 



This variety, as determined by M. E. Deslongchamps, is more circular and spherical, 

 or regularly convex, than the var. Smithii, and less transverse than the following 

 variety called Thurmanni ; the fold in the dorsal valve does not rise in so marked or 



