ATHYRIS. 217 



diate connecting lamellae are similarly disposed in Athyris ambigua to those of A. pcctini 

 /era, of which we have also given a representation in the same plate. 



Athyris subtilita. 1 Plate I, figs. 21, 22 ; and Plate XVII, figs. 8, 9, 10. 



In p. 18 I have described the shell as a Terebratula, but in p. 86 located it with 

 Athyris, to which genus it belongs. 



Athyris lamellosa (p. 79). Plate XVI, fig. lj Plate XVII, figs. 6, 7 ; and Plate LI, fig. 14. 



When describing this species in p. 79 I had not seen any specimens with its concentric 

 lamelliform expansions completely preserved, and it was only subsequently that Mr. J. 

 Wright discovered several fine examples at Little Island, near Cork (PI. LI, fig. 14), 

 showing that these expansions were prolonged in some specimens nearly an inch from the 

 surface of the shell, and that they differed from those which adorned the valves of Athyris 

 plano-sulcata by being somewhat irregularly plaited, or frill-like, as seen in PI. LI, fig. 14. 



Athyris plano-sulcata (p. 80). Plate XVI, figs. 2 — 15 ; and Plate LI, figs. 1 — 13. 



This species appears to have varied considerably, and I have already shown that the 

 original A. virgoides, M'Coy, is nothing more than an elongated shape of the present 

 species, distorted from pressure and cleavage. 



Athyris Carringtoniana, Dav. Plate LII, figs. 18 — 20. 



Sp. Char. Shell transverse, sub-rhomboidal, with rounded extremities ; wider than 

 long ; valves moderately convex, and about equally deep ; hinge line, forming an obtuse 

 angle, the greatest breadth of the shell being along the middle ; beak of ventral valve 

 small, slightly incurved ; foramen circular, and contiguous to the umbone of the opposite 

 valve ; beak ridges sharply defined, leaving between them and the hinge line a narrow 

 flattened space. A shallow longitudinal sinus or furrow extends from the extremity of the 

 beak to the front. In the dorsal valve there exists a moderately elevated mesial fold, 

 longitudinally divided by a shallow furrow. Externally both valves are regularly traversed 

 by continuous concentric small ridges or striae. Dimensions variable: two specimens have 

 measured — 



Length S, width 14, depth 6 lines. 



1 The reference is not quite correctly given at p. 86, it should be Hall, in Howard Stansbury's 

 ♦Exploration of the Valley of the Great Salt Lake of Utah,' p. 409, pi. 2, figs. 1-2 : 1852. 



