100 SHELLS AND SHELL-FISH. PART I. 



Analogies of the VOLUTIDJE and the CASSID.E. 



Sub-families of Sub-families of 



VoLUTiaE. Analogical Characters. CASSID.E. 



Typical Genera. Typical Genera. 



VOLUTA. Smooth j spire[short ; base truncate. CASSIS. 



MITRA. 



r Aperture very wide ; the base of f 

 ANCILLARIA. < the pillar often thickened and >- PURPURA. 



i striated. 3 



CA thick deposition surrounding} M A O C . 



MARGINELLA. the aperture of the shell. j 



This table illustrates what has been often shown 

 among the vertebrated animals, that, to establish the 

 analogies of two given groups, they must often be traced 

 through the medium of other groups : thus, the Ancil- 

 laria, in one respect, are prototypes of the Cypraa; and 

 in another, by their wide aperture and striated base, are 

 equally so to the Purpurce. Again, if it was asked,- 

 What shells among the volutes have a marked resem- 

 blance to Concholepas and Monoceros ? every natural- 

 ist would point to Ancillaria ; for all three have a very 

 wide aperture, and a distinct prominent tooth at the base 

 of the outer lip. This is conclusive evidence ; and it 

 therefore follows that the analogy between Ancillaria 

 and Cyprcea, however obscure in a direct way, is ren- 

 dered plain by being traced through the medium of the 

 Purpurinfe. The other analogies in the table are so 

 palpable to the zoologist, that they require no illustra- 

 tion. Hence it follows, as a natural result of this com- 

 parison, that the Volutida, in like manner, represent 

 all other of the circular groups in the zoophagous 

 tribe. 



(90.) Our next object is to show that the Volutidce, 

 as a whole, form a circle of affinity. It is clear that the 

 pre-eminently typical volutes, or melon-shells, branch 

 off into two separate series ; one leading to Scaphella, 

 through V. magnified, fulgetrum, papillaris, and fusL 



