100 



SHELLS AND SHELL-FISH, 



Analogies of the Volutid^ ajid the Cassid.e. 



Sub-families of 



VOLUTID^. 



Typical Genera. 



VOLITA. 

 MiTRA. 



Oliva. 



Anctllxria. 

 Marginella. 



Analogical Characters. 



Smooth; spire'short ; base truncate. 

 f Rough ; spire longer j base atte- 7 

 l nuated. J 



r Foot very large ; no distinct plaits 7 

 I on the pillar. J 



r Aperture very wide ; the base of T 

 ^ the pillar often thickened and >■ 

 C striated. j 



5" A thick deposition surrounding 7 

 t file aperture of the shell. J 



Sub-families of 



CASSID.E. 



Typical Genera. 

 Cassis. 



MUREX. 



Purpura. 



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- 

 laricp, in one respect, are prototypes of the CyprcecBj 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 Ciiprcpa, however obscure in a direct way, is ren- 

 dered plain by being traced through the medium of the 

 Purpurincp. 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 Volutidce, in like manner, represent 

 all other of the circular groups in the zoophagous 

 tribe. 



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

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

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

 ofFinto two separate series; — one leading to Scaphella, 

 through V. magivficn, fulgetrmn, papillaris, and fusi. 



