CHAP. V. STROMBIDiE. 13? 



(125.) The rank of the group being that of a family, 

 its first divisions, just mentioned, become sub-families. 

 1. The StromhincB, or true wing. shells, having the outer 

 lip greatly dilated, with a lobe at the base, and often on 

 the summit also, of the outer hp ; the spire being always 

 more or less elevated. 2. The Conince, or Cones, where 

 the spire is so depressed as to be turbinated, and scarcely 

 raised above the body-whorl : the aperture is always 

 smooth ; the outer lip without any lobe, and only 

 slightly detached above. 3. The Columbellince, or dove- 

 shells, small in size, and with short-pointed spires ; 

 the outer lip is thick, turned inwards, more or less 

 toothed on its edge, and gibbous above ; there are also 

 tuberculated teeth at the base of the inner lip, but no 

 regular plaits. 4. The Pleurotomijice, or slit-shells, — 

 so called from a deep lobe, or slit, at the top of the 

 outer lip : the spire, in general, is very long, and the 

 shells themselves often spindle-shaped. 5. The Ceri.. 

 thince, called club-shells, from their clavate form : the 

 body-whorl is not much larger than the one which 

 precedes it ; but the outer lip is slightly detached 

 above, and then much dilated ; the basal canal, which 

 is always very short, is generally more or less turned 

 backwards. 



(126.) These primary divisions appear to form a 

 circular series, and to be united in the following man- 

 ner : — Commencing with the Stromhince, we pass from 

 them to the CerithincB, by means of that well-known 

 shell the S. pes-pelicani of Linnaeus, which, in its im- 

 mature state, before its lip has expanded, might easily 

 be mistaken for a young Cerithium. Next to these 

 latter, Lamarck places the PleurotomincB ; their junc- 

 tion being formed by his Clavatula, and the genus 

 Potomis : with these, again, a union is rendered abso- 

 lutely perfect with the Co/utnbina', by means of certain 

 genera now defined for the first time : others of the 

 Columbincp so strikingly resemble small cones, that but 

 for a close inspection, they could not be distinguished. 

 From the cones we pass to the singular genus Tercbellum, 



