a 
146 Dr. ©. W. Andrews on 
seventh marginals. The width has clearly been somewhat 
exaggerated by the flattening that the shell has undergone, 
but probably even in an uncrushed state the convexity of the 
carapace was comparatively slight. The anterior border is 
concave in the middle; then, external to this, the outline as 
far as the ninth marginal forms nearly the are of a circle; 
Tholemys passmorei, gen. et sp.n. Diagram of dorsal aspect of the 
carapace of the type-specimen. j nat. size. 
¢,-¢,, costal shields; W\—N;, neural bones; Nw., nuchal bone; zw., nuchal 
shield; Pyg., pygal bone; S.pg.', S.pg.’, first and second supra- 
pygal bones ; v1-v5, vertebral shields. 
behind this there is a slight concavity and the posterior 
border of the shell is broadly convex. 
The nuchal bone has a concave anterior border ; its width 
(104 mm.) is about three times its length on the middle line. 
The first neural bone seems to have been comparatively 
