EXPLANATION OF PLATE XLV1I. 



Crioceras plectoides, Eth. fil. 



Fig. 1. Lateral view of a neat and well preserved partially testiferous 

 specimen illustrating the principal characters of the species. 



,, 2. Ventral view of Fig. 1, exhibiting the wide and rounded venter. 



,, .'}. Ventrodorsal view of Figs. 1 and 2, displaying the broad rounded 

 venter, overhanging whorls, and nearly round section. 



,, 4. Lateral view of portion of a natural cast whorl corresponding in 

 size to the subject of Plate xlvi., fig. 1 ; an almost complete suture 

 is here visible. 



Crioceras, sp. 



,, 5. Lateral view of the specimen represented in Plate xxxv., fig. 2, 

 exhibiting the dorso-lateral line of tubercles (see Plate xxxv., fig. 2; 

 PI. xlii., fig. 1; and PI. xlvi., fig. 2). Seven-twelfths the natural 

 size. 



