PALtEOCORYSTES. 15 



very imperfect specimens. Professor M'Coy does not appear to have been aware of these 

 figures, or of the names and description given by Mantell in the ' Medals,' as he makes no 

 mention whatever of this species. It is found in considerable numbers in the Gault at 

 Folkestone, and Dr. Mantell's specimens were from Maidstone, and from Ringmer in 

 Sussex. 



Pal^^ocorystes Stokesii, Mantell, sp. Plate III, figs. 1 — 9. 



Testa tuberculata, carinata ; margine latero-anteriori quadridentato ; regionis cardiacfB 

 mars;ine anteriore tuberculo unico instructa. 



CoRYSTES, sp., Mantell. Geol. Suss., t. xxix, figs. 15, 16. Geol. S.E. Engl., p. 169, 

 fig. 3. 

 -i- Stokesii, Id. Medals of Great., p. 532, fig. 2. 

 NoTOPOCOEYSTES Mantelli, M'Coy. Ann. Nat. Hist., 1849, p. 170. 

 — Stokesii, Morris. Cat., p. 111. 



Bescr. Carapace ovate, carinated, the surface minutely granulated ; regions rather 

 more distinct than in the former species, and beset with numerous tubercles, of which there 

 is a regular series of seven or eight on the median carina, those on the cardiac region pro- 

 minent and sharp, a single one being placed in the centre of its anterior margin ; there 

 are three or four conspicuous ones on the lateral lobes of the gastric and on the hepatic 

 regions, and one on the mesobranchial lobe ; nuchal furrow deeper than in P. Broderipii ; 

 the anterior process of the mesogastric lobe very narrow, extending to the base of the 

 rostrum, with a thin sulcus on each side ; front terminating in a small bidentate rostrum, 

 which is depressed in the middle, and has two smaller teeth immediately above and 

 behind the terminal ones ; orbits of moderate size, not extending so far laterally as in the 

 former species, with two shallow fissures above ; latero-anterior margin with four strong, 

 prominent teeth, curved forwards ; latero-posterior margin regularly, but very slightly, 

 curved ; posterior margin less hollowed than in P. Broderipii ; pterygostomian process 

 tumid, deeply sulcate, the ridges with numerous tubercles ; buccal opening narrower than 

 in the former species. External footjaws with the outer stalk narrow, flat, slightly 

 curved inwards; the inner stalk with the second joint a little wider anteriorly, and longi- 

 tudinally grooved, the third joint nearly twice as long as it is broad, grooved, and widened 

 forwards, inserted at the middle of the anterior margin of the second joint. The legs 

 are of moderate size, rather long, and varying in thickness in different individuals, which 

 may possibly be dependent upon sex. The claws are somewhat flattened, angular ; the 

 arm furnished with a few small tubercles on the outer and inner margin, and two or three 

 near the distal extremity; the wrist is angular, carinated, and sparsely tuberculated ; the 

 hand has three distinctly tulierculated carina), the lower of which runs along the im- 

 moveable finger. The abdomen is about half as broad again in the female as in the 



