62 SHELLS AND SHELL-FISH. PART I. 



shell. The first would include, like the old systems, 

 all manner of spiral shells, under the generic name of 

 Buccinum ; while the other would place Parmophorus, 

 Fissurella, and Umbrella in the same group as the 

 limpet, merely because they had similar shaped shells. 

 While, therefore, we make this and all our other chief 

 divisions to repose on a primary consideration of the 

 soft parts of the body, we regard the construction of the 

 shell as much a part and parcel of the animal itself, as 

 are the wings of an insect or the hard covering of the 

 chelonian reptiles. The shell of testaceous animals, in 

 fact, is precisely analogous to the covering of the 

 tortoises, and are to be considered in the same light, 

 that is, furnishing a secondary, although a very im- 

 portant, set of characters for the determination of the 

 minor groups. It is not a little remarkable that, as the 

 tribe before us is the most completely organised, and 

 therefore the most typical of the whole of the Testacea, 

 so do we find their testaceous coverings are the most 

 complicated, and by far the most beautiful of all the 

 spiral' univalves. The gradual transitions of form whicji 

 they present, even when there is little or no variation in 

 the animal, or, at least, none that has yet been detected, 

 is a clear proof, if any other was wanting, that all our 

 secondary characters taken from the shell, are those 

 which nature herself has employed to designate the sub- 

 ordinate groups. The definitions, therefore, of the 

 families in which we shall now arrange this tribe, will 

 be mainly taken from the shell, at the same time intro- 

 ducing all such information regarding the soft parts of 

 the inhabitant as appear of primary consequence. 



(54.) The five leading divisions of the Zoophaga may 

 be thus named and defined : 1 . The MURICID.E, or 

 murexes, having the respiratory siphon in general very 

 much developed, and its corresponding canal at the base 

 of the shell always straight. 2. The TURBINELLID^E, 

 or turnip -shells, where the base of the shell is straight 

 and lengthened, and the pillar strongly plaited. In both 

 these, the mantle of the animal is never dilated, but is 



