EXPLANATION OF THE PLATES AND WOOD-CUTS. 



Turbinated or cylindrical ; terminal cup occasionally very deep, occasionally 

 shallow, covered with bladder-like tubercles, traversed in some specimens by radi- 

 ating lamellse ; external surface marked with concentric rugae and faint vertical 

 lines ; internal structure very irregularly vesicular, often without any indications 

 of radiating lamellae ; but in some specimens there are indications of them (Fig. 

 11 b.), and in others they are quite distinct (Fig. 11 a.). 

 Fig. 1 1 represents a portion of a fine group, with three young corals attached to the 

 side of an old one. 



Loc. Newton Bushel, very abundant, the coral occurs also at Plymouth. 



WOOD-CUT. 



Section from the Foreland in the Bristol Channel to the English Channel : p. 702. 



Plates LIX. and LX. 

 Illustrate Mr. Stokes's paper on some species of Orthocerata : p. 705. 



Plate LIX. 



Fig. 1 . Actinoceras Lyonii, p. 707. 



Figs. 2 and 3. Actinoceras Richardsonii, longitudinal and transverse sections, p. 708. 



Fig. 4. Actinoceras Simmsii, one third the natural size, p. 708. 



Fig. 5. Transverse section oi Actinoceras Simmsii, p. 708, and note f, also p. 712. 



Fig. 6. Magnified portion of the coral investing A. Simmsii, p. 708, note f , and p. 712. 



Plate LX. 



Fig. 1. Ormoceras Bayfieldii, p. 709. 



Fig. 2 and 3. Longitudinal sections oi Huronice, p. 710. 



Fig. 4. Exhibits a peculiarity in the structure of Orthocerata. The specimen is from 



Russia, p. 712. 

 Fig. 5. Huronia Portlockii, p. 710. 



Plate LXL 



Illustrates Col. Sykes's paper on fossils procured by Capt. Smee and Col. Pottinger in 

 Cutch and the Desert to the north-east of Cutch, p. 715. The shells have been 

 engraved and the description prepared by Mr. James de Carle Sowerby, F.L.S. 



Fig 1 . Astarte major. Elliptical, convex, concentrically furrowed when young ; fur- 

 rows numerous ; beaks small, near the antei'ior side ; lunette broad, flat, deeply 

 sunk ; ligament long, sunk. Length from 2 inches 4 lines to 2 inches 8 lines, 

 width 4i inches. 



This species varies much in the proportions of its length and breadth, and the 

 anterior side is sometimes formed as if truncated. The figure represents a very 

 wide variety diminished to frds its size. 



1 



