CLASSIFICATION. 73 



some of the Muricinse have the operculum and short canal of the 

 Purpuringe, whilst some of the latter possess the varices of the 

 former. 



In the following synopsis of genera and subgenera, the dis- 

 criminative characters used separate widely groups, which really 

 appear to be closely related : thus, Cerostoma and Pteronotus 

 are intimately allied, notwithstanding the difference of the oper- 

 culnm ; and Phyllonotus and Chicoreus have the same general 

 facies, although they differ in the number of varices. Owing to 

 their inter-relationships, no attempt to present the genera in suc- 

 cession can be other than exceedingly artificial. 



Sub-Family MURICIN^E. 



Synopsis of Genera. 



MUKEX. Shell ovate or oblong ; spire prominent ; whorls convex, 

 crossed by three or more continuous varices ; aperture ending below in 

 a canal, which is generally partly closed. 



a. Operculum with sub-apical nucleus. 



* Varices three. 



Typical Murices. Shell spinous ; spire elevated ; canal very long, 



narrow, nearly straight. 

 Subgenus PTERONOTUS. Shell triangular ; varices fin-like or foliated ; 



canal moderate, closed, somewhat curved. 

 Subgenus CHICOREUS. Shell ovate-pyriform ; varices foliated and 



sometimes spinose ; canal short, curved, wide, nearly closed. 



* * Varices four to ten. 



Subgenus RHINOCANTHA. Has the short body whorl and long canal of 

 the typical murices ; differs in having more numerous varices. 



Subgenus HOMALOCANTHA. Whorls rounded and sutures very deep ; 

 varices foliated, and peculiarly produced into expanded digitations ; 

 canal long. 



Subgenus PHYLLONOTUS. Like Chicereus, but varices numerous. 



b. Operculum purpuroid. 



* Varices three. 



Subgeuus CEROBTOMA. Varices wing-like ; aperture usually dentate 

 within the outer lip, with a produced tooth near its base. Analogous 

 with Pteronotus. 

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