BRACHIOPODA. 



313 



Genus LYTTONIA, Waagen. 1883. 



1S78. Baiirynium, Waagen. Rei:oi-ds Geol. Sui-v. India, vol. xi, pp. ISfi, 187. 



1880. Thecidea, Zugmayer. Unters. iiber ihat. Brachiopoden ; Beitr. ziir Palaon. von Oesterreich- 

 Ungai-n, I, ji. 22. 



1882. Leptodns, Kayseh. Richthofen's China, vol. iv, p. 161. 



1883. Lyttonia, Waagen. Pi-odnctua-Iimestone Fossils; Brachiopoda, [ip. 396-40S, pi. xxix, figs. 1-3; 



pi. XXX, figs. 1-11. 



Shells of great size, highly inequivalve and very irregular ; frequently with 

 broad lateral expansions. 



Pedicle- valve convex, thick ; apex not distinct; hinge-line short and straight ; 

 teeth faintly developed. On the interior are numerous ridges extending in 

 slight curves toward the lateral margins; in the median line is a smooth space 

 bearing a central vertical ridge. 



Fi(j. '.'43. Fk;. 244. 



Lyttonia nobilis, Waagen. 

 Fig. 243. Cardinal part of a poilicle-valve; showing the hinge-line, median and lateral septa. 

 Fig. 244, A portion of the interior of a brachial valve. (WAAGEN.) 



Brachial valve operculiform, not extending to the margins of the opposite 

 valve. Cardinal process small and bilobed ; median surface of the interior 

 with divergent grooves corresponding with the ridges of the other valve. 



External surface covered with flexuous lines of growth. 



Shell-substance punctate in the inner layers. 



Type, Lyttonia nobilis, Waagen. Carboniferous. India and China. 



