BRACHIOPODA. 
313 
Genus LYTTONIA, Waagen. 1883. 
1878. Bactrynium, Waagen. Records Geol. Surv. India, vol. xi, pp. 186, 187. 
1880. Thecidea, Zugmayer. Unters. iiher rhat. Braohiopoden ; Beitr. zur Palaon. von Oesterreich- 
Ungarn, I, p. 22. 
1882. Leptodns, Kayser. Richthofen’s China, vol. iv, p. 161. 
1883. Lyttonia, Waagen. Productus-limestone Fossils; Brachiopoda, jip. 396-403, 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. 
Fig. 243. Fig. 244. 
I/yttonia nohilis, Waagen. 
Fig. 243. Cardinal part of a pedicle-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 nohilis, Waagen. Carboniferous. India and China. 
