some British Fossil Crustacea. 



169 



small and smooth, second, third and fourth each with a pair 

 of tubercles on the elevated middle portion, fifth smooth, with 

 a small triangular piece (remains of the embryonic tail-tin) 

 on each side between it and the sixth or last joint, which is 

 subpentagonal and rather more than twice the length of the 

 fifth ; tail of the female broad ovate, smooth, trilobed ; ante- 

 rior pair of feet forming short robust chelse, with scattered spi- 

 nose tubercles ; the others small and smooth, the two hinder 

 pair abruptly smaller and elevated above the rest. Length of 

 carapace 10 lines, width 9 lines. 



Common in the London clay of Sheppey. 



{Col. University of Cambridge and Mr. Bowerbank.) 



Notopocorystes (M^Coy), n. g. 



Etym. vcSto?, dorsum, irov^, pes, and Corystes. 



Gen. Char. Carapace longer than broad, ovate, depressed, with 

 scattered tubercles, anterior half broadly rounded and fur- 

 nished with a few strong marginal teeth; 

 posterior lateral margins acute, straight, 

 rapidly converging towards the base, 

 which is narrow and deeply emarginate ; 

 front forming a short triangular rostrum, 

 depressed in the middle, and with a small 

 mesial ridge; orbits large, transversely 

 oval, complete below and above, with two 

 longitudinal fissures in the upper margin; 

 gastric region very large, rhomboidal, de- 

 fined posteriorly by a strong obtusely an- 

 gular nuchal furrow pointing backwards, 

 slightly convex, extending nearly the width 

 of the carapace, leaving a very small ob- 

 scurely defined hepatic region on each side; 

 genital region very small, about twice as wide as long, not 

 dividing the gastric region ; cardiac region moderately large, 

 hexagonal, with a small deep lunate fossa on each side at its 

 junction with the genital region ; intestinal region narrow ; 

 branchial regions large, each divided by a shallow furrow pro- 

 ceeding from the base of the genital region to the lateral mar- 

 gin on each side, parallel with the nuchal furrow; pterygostomian 

 regions very tumid ; first pair of feet short, robust, didactyle 

 spinulose ; tifth pair of feet disproportionally small and elevated 

 above the level of the others ; abdomen of the male narrow 

 (? six-jointed). 



This Uttle genus completes the chain of affinities between the 

 recent genera Homola and Corystes, rendering the transition per- 



Back view and profile 

 of Notopocorystes. 



