EXPLANATION OF PLATE XXXVIII. 



Crioceras, sp, 



Fig. 1. Lateral portion of a whorl with direct, or very faintly sigmoidal, 

 sharp costae, each bearing a simple pimple-like node. 



,, 2. Ventral view of Fig. 1 ; the costte are very slightly bent forwards. 



Crioceras jackii, Eth. fil. 



,, 3. Lateral view of the older whorls with obtuse thick costse, but those 

 tubercle-bearing more swollen than the others. Careful inspection 

 of the innermost revolution will reveal the three rows of tubercles, 

 the dorsal first dying out, then the lateral (supra-dorsal), and 

 finally the abdominal row at about the twelfth costa before the 

 distal fractured end. 



,, 4. Lateral view of a shell rather larger than that represented in Fig.3, 

 with very regular thick costa;, here and there slightly sigmoidal. 

 No tubercles visible. 



,, 5. Ventral view of Fig. 4. 



