14 FOSSIL MALACOSTRACOUS CRUSTACEA. 



do not remember to have seen the same circumstance in any of the existing Brachyura. I 

 have figured a specimen thus infested in Plate III, fig. 3. 



PALiEocoRYSTES Broderipii, sp., MctnfcU. Plate II, figs. 8 — 13. 



Char. Gen. Testa depressa, la;vi ; margine latero-anterioro tridentato. 



CoRYSTES, sp., Mantell. Gcol. of Sussex, t. xxix, figs. 9, 10. Geol. of the S.E. of 

 Eng., p. 170. 

 — Broderipii, Id. Medals of the Creation, p. 532, fig. 3. 

 NoTopocoRYSTES Brouekipii, Morrw. Cat., p. 111. 



DescT. Carapace flattened, smooth, mimitely granulated, about one fifth longer than 

 it is broad, becoming gradually narrower backwards from the third lateral tooth ; the 

 regions very indistinct; the hepatic with two small depressed tubercles ; nuchal furrow 

 extremely shallow and small, placed very far forward on the carapace ; the anterior process 

 of the metagastric lobe very narrow and attenuated, extending forward to the base of the 

 rostrum, with a thin sulcus on each side ; branchial region occupying two thirds of the 

 whole length of the carapace, separated from the cardiac by a curved furrow; front with 

 a distinctly bidentate rostrum, which is depressed in the middle ; orbits extending laterally 

 to near the anterior angle of the carapace, with two fissures and a triangular tooth between 

 them on the superior margin ; latero-anterior margin with three strong triangular teeth, 

 including the external orbital process, and a slight projection behind them, from which 

 commences a sharp marginal ridge ; the posterior margin hollowed ; the ptcrygostomian 

 processes tumid, sulcated, and with two carinas, the superior of which has a line of small 

 tubercles. The buccal opening twice as long as it is broad, narrowed forwards, and 

 extending nearly to the base of the rostrum, the epistome being extremely small. 

 External footjaws with the outer stalk slightly curved. The third joint of the inner stalk 

 straight, linear, and flat. The anterior segment of the thorax terminating in three 

 small, flattened processes. Legs similar to those of P. Stokesii ; the anterior pair 

 short and smooth, the fingers short and inflected, to a degree, however, which varies in 

 different specimens, possibly dependent on sex ; the ambulatory legs nearly cylindrical, the 

 third joint with a series of small spines on the anterior side. The abdomen in the male 

 narrower than in the female, carinated, the first segment rather longer than the four 

 succeeding ones ; the second, third, fourth, and fifth short, each with a small central spine 

 or tubercle, the sixth forming a large quadrate piece, the seventh triangularly semioval. 



Length of carapace, 1-4 inch; breadth, 12 inch. 



It occurs in the Gault at Polkestone and Maidstone, in Kent, and at Ringmer, in Sussex, 

 in considerable nunil)ers. 



Obs. This species was first figured by Dr. Mantell, in the ' Geology of Sussex,' and 

 afterwards in the ' ■Medals of Ci'cation.' The figures are very inferior, and taken from 



