()6 SHELLS AND SHELL-FISH. PART I. 



(84.) The genus Buccinum andthe aberrant genera of 

 Fusus are so much ahke, that they can only be distin- 

 guished by the latter, as Chrysodomus, having the basal 

 canal slightly produced instead of truncated. These two 

 divisions are further remarkable for containing those 

 genera which, by the length of their spire, contain the 

 longest-bodied Testacea in the whole tribe. But for 

 its elongated canal, Fusus colus and its allies would 

 become TerehrcB ; while, but for their truncated base, 

 these latter would be placed among the Fusince. The 

 remarkable analogies between the PurpurincB and the 

 Pyrulincp. (4. 4.), having already been so much enlarged 

 upon, need not be again repeated. The only remaining 

 comparison concerns the EburninfS and the Nassince, 

 — 'two groups so closely related to each other in their 

 typical examples, that even Lamarck, mistaking ana- 

 logy for affinity, actually places them following each 

 other : both, in fact, have the base of the shell obtuse, 

 without any elongation ; the inner lip very thick, and a 

 strong internal groove within the aperture. But it is 

 needless to insist upon an analogy so indisputable : we 

 may, therefore, presume, that in these two comprehensive 

 groups we have made good all our propositions on the 

 laws of the natural system * ; and we shall now endea- 

 vour to do the same in the succeeding families of the 

 Gasteropoda. 



* The Geography and Classification of Animals^ Part iii. On the First 

 Principles of natural .Classification, p. ,221. Vol. LXVl. of the Cabinet 



CvCLOPJiDlA. 



