BRACHIOPODA. 113 



continuing into the layers beneath, but producing a superficial ornamentation not 

 unlike that occurring in Eichwaldia. This ornamented layer extends even over 

 the surface of the deltidium. The inner laminae of the shell are fibrous and 

 more sparsely punctated. There is no deltidial tube in the umbonal cavity of 

 the pedicle-valve. The hinge-plate has not been completely demonstrated, but 

 it appears to be similar to that of Rhynchospira, with no prominent posterior 

 extension, but with conspicuous crural bases which are curved upward. The 

 whole process is supported by a well defined median septum. The spiral rib- 

 bon makes but few (four or five) volutions ; the loop takes its origin behind 

 the middle of the primary lamellae, its lateral branches being slightly constricted 

 near their bases ; it is inclined backward in a broad curve, the union of the 

 lateral branches taking place at a point just within 

 the opposite side of the base of the cones. From 

 this point the stem of the loop is continued as a 

 simple process, outward between the coils and 



, . . .t • n f ii T 1 1 Fig. lOJ. The )oo\) ot Ptychospira/erita, 



almost to the inner surface ot the pedicle-valve. von Buch. (o 



Genus UNCITES, Defrance. 1827. 



PLATE UI. 



1776. Terebratula, Bboth. Jiilise et Montium Subterranea, etc., p. 134. 



1822. TerdyratulUen, Schlothkim. Petrefacktenkunde, pi. xix, tig. 1. 



1827. U7icite.i, Dkfbanck. Bull, des Sciences, vol, xii, p. 152. 



1834. Terebratula, von Bdch. Ueber Terebrateln, p. 69. 



1851. Unc'ites, Qobmstkdt. Handbuch der Peti-efacktenkunde,"p. 459, pi. xxxvi, figf. 40. 



18SS. Uneites, Davidsox. Introd. British Fossil Bi-achiopoda, p. 89, pi. vii, tigs. 79-8G. 



1855. UncUes, Thb Sakdbbsobrs. Verslein. der ihein. Schicht. Syst. Nassau, p. 333, pi. xxxi, fig. 5. 



1864. VticUes, Davidson. British Devonian Brachiopoda, p. 22, pi. iv, figs. 11, 12. 



1871. Urtcites, Qok.v.stbdt. Petrefacktenkunde Deutschl.; Brachiopoden, p. 231, pi. xliii, figp. 46-55. 



1881. Unciten, Davidson. Geological Magazine, new ser., vol. viii, p. 145. 



1882. UncUes, Davidson. British Devonian Brachiopoda, Supple., p. 30, figs. 1, 2. 



Diagnosis. Shells usually of large size, elongate-oval or subtriangular in 

 marginal outline ; valves convex. The pedicle-valve has a long and acuminate 

 beak which is always arched or incurved and frequently distorted. There is 

 no cardinal area and the hinge-line is greatly curved. There is no foramen in 

 mature individuals though it may be retained in young forms. The deltidium 

 is concave and consists of a single piece, all trace of the original components 



