PLATE II. 



(Permian Species.) 

 Fig. 



1. Athyris pectinifera, J. de C. Sowerby. Interior. Humbleton. 



2. — — This beautiful (magnified) illustration of the interior is entirely drawn 



from nature, but not from a single specimen. The hinge-plate 

 and its small circular aperture, as well as the dental or rostral plates, 

 have been taken from specimens in the possession of Professor King 

 and Mr. Kirkby. The spirals are from a perfect example discovered 

 by Mr. Howse at Humbleton hill. The spinose expansions are copied 

 from two or three specimens in the cabinet of Mr. Kirkby. This 

 illustration, while correct in its different parts, conveys a clear idea of 

 the complicated internal arrangement. 



3. — — The central portion of the spirals, considerably magnified, to show the 



connecting processes more clearly than in fig. 2. 



4. — — A portion of the spiral and connecting process, seen as if the beaks had 



been removed. 



5. — — A fragment of the spiral lamella, showing the spines on its outer edge. 



6. 7. Spirifera alata, Schlotheim. Internal cast of the ventral valve, to show the adductor (a) 



and cardinal (r) muscular impressions, as well as the ovarian 

 spaces (o), from specimens in the collections of Mr. Howse and 

 Mr. Kirkby. 



8. Terebratula elongata, Schloth., var. svfflata. Internal cast from a typical example. Humbleton 



hill. 



9. Camarophoria Humbletonensis, Howse = multiplicata, King. Internal cast, showing portions of 



the narrow marginal expansions peculiar to this species. Humbleton. 

 Collection of Mr. Howse. 



10. — — Front of a very large individual. 



11. — — Internal cast, 6een from the beaks, in which the impressions referred to 



the adductor (a) and cardinal muscles (r) ? are exposed. Humbleton 

 hill. Collection of Mr. Howse. 



12. — — Internal cast of the ventral valve, showing the cardinal (?) muscular 



impressions, and the raised band (t) observable in many individuals, 

 but which remains still unexplained. Humbleton. Collection of 

 Mr. Howse. 



13. 14. — — Internal casts, from Humbleton, exhibiting the vascular impressions. 



Collection of Mr. Howse. 

 15. — — Interior of the dorsal valve, enlarged. 



16 — 18. — Schlotheimi, V. Buck. Different ages. Tunstall hill. 



19. — — A var. with only two ribs on the mesial fold, and thus hardly distinguish- 



able, except in dimensions, from C. globulina. Tunstall. 



20. — — A trigonal-shaped specimen, with hardly any indication of ribs, and thus 



approaching to T. superstes, De Verneuil. Tunstall. 



21. — — A specimen, showing the large dimensions of the marginal expansions. 



Tunstall. Collection of Mr. Kirkby. 



22. — — Cast of the ventral valve, exhibiting the marginal expansions. Humbleton 



hill. Collection of Mr. Kirkby. 



