CHAP. IV. CIRCLE 1F VdDUVIDJSB- 



formis ; the other to CymUola, or the muricated volutes. 

 From this latter, therefore, we shall begin to trace our 

 circle ; because, even here, we have evidently a repeti- 

 tion of the analogy between the smooth helmets and 

 the spined murexes. After the Cymbiolce, or muricated 

 volutes, succeed such as have the spire elongated, and 

 the plaits upon the pillar numerous : among them is the 

 Valuta lyriformis ; and this brings us at once into the 

 sub-family of the mitres : from these the passage to the 

 olives is rendered so gradual, by Mitrella in one, and 

 Olivella in the other, that the mere systematist will 

 hardly admit these genera, because they blend into each 

 other. Hiatula is in the same predicament : by its wide 

 mouth, and the thickened base of its pillar, it is all but 

 an Ancillaria; so that the junction is here also complete. 

 There remains, then, only the Marginellte, which are so 

 like some of the Ancillarice, that we may safely place 

 them as next in the series. What group then succeeds ? 

 The illustrious Lamarck considered the well-known 

 Voluta Zebra (fig. 7- ) of 

 our catalogues to be so like a 

 Marginella, that he has actually 

 placed it in that genus: and 

 the affinity between this shell 

 and Scaphella maculata (6) is 

 immediate : we thus pass to the 

 S. fulgetrum, and again reach 

 the typical volutes. Thus, by 

 a different route, we return to 

 the point from which we started, without a link in the 

 chain being wanting. 



(91.) We have thus shown that the Volutidce form 

 a perfect circle of affinity ; and that the divisions we 

 have thrown them into are strictly natural, because they 

 are prototypes of all the others in the zoophagous tribe. 

 Each of these primary groups, or sub-families, will now 

 be examined in detail, in the order in which they na- 

 turally follow ; viz., the VOLUTIN^:, the MITRINJE, the 

 OLIVIN^E, the ANCILLARIN.E, and the MARGINELLIN^:. 

 H 3 



