116 SHELLS AND SHELL-FISH. PARTI. 



will call to mind the smooth and the coronated helmets 

 (Cassidea and Dolium}, the smooth Turbinellce, and 

 the murex-like Scolymince, the tuberculated StromU, 

 and the smooth Cones. The same principle, again, is often 

 carried into the variation of each : thus, although the 

 Cones, as a whole, are smooth shells, yet one division has 

 coronated tubercles. Some of the melon volutes are 

 smooth, as V. Neptuni; while others (which are sub- 

 typical) are coronated. Every division, in short, large 

 or small, in the entire family of volutes, exhibits these 

 differences. The reader will of course understand we 

 are now speaking only of the typical and the sub-typical 

 types ; the variation of the aberrant forms being regu- 

 lated by other circumstances, which, in the present state 

 of our inquiries, it would be premature to venture upon. 

 (105.) If the foregoing arrangement of the sub-ge- 

 neric types of Valuta be really natural, it follows that all 

 the melon volutes form but one sub-genus. Break them 

 up into other sub-genera, and give to each the same 

 rank as attaches to the four other types, and the whole 

 harmony and beauty of the theory would obviously be de- 

 stroyed ; their arrangement would then, in fact, become 

 an arbitrary matter of nomenclature. Had our object been 

 to have formed an artificial classification of the Testacea, 

 we should, without hesitation, have adopted the views 

 of others on this subject. The divisions of the smooth 

 and the coronated melons are excellent, because they are 

 natural : but all we have now stated shows that they 

 are two sections only of a sub-genus. It will be evi- 

 dent to those zoologists who may be conversant with 

 the vertebrated animals, that all groups pre-eminently 

 typical contain a greater number of forms than any other, 

 as if Nature intended to show us, at the onset, the rudi- 

 ments of all those variations which were to characterise 

 the surrounding groups. Lawrence, long ago, observed 

 of the Caucasian race of man, the most pre-eminently 

 typical, that it contained more numerous variations 

 than any other; and we have shown how strictly 

 applicable this assertion to the vertebrated animals. 



