EXPLANATION OF PLATE XXXI. 



Figure 233. — Crenella glandula, (p. 695.) 

 234.— Mytilus edulis, (p. 692.) 

 235. — Modiolaria corrugata, (p. 694.) 

 236. — Modiolaria nigra, (p. 694.) 

 237.— Modiola raodiolus, (p. 693.) 

 238.— Modiola plicatula, (p. 693.) 



(All the figures are of natural size, and from Binney's Gould, drawn by E. S, Morse.) 



