of mollusca. 37 



13. Persictjla. 



Shell oblong ; spire short, hidden ; mouth linear ; pillar with 

 numerous cross grooves ; outer lip thickened externally. Mantle 

 covering three-fourths of the shell. 



a. Inner lip simple. 



1. P. cameola?, t. 102. f. 3, copied Adams, Gen. Moll. t. 20. f. 3. 



2. P. lineata, t. 4. f. 4. 



(i. Inner lip callous, with a large cross fold in front ; outer lip 

 crenulated. Rabicea. 



3. P. interrupta. 



D. Tsenioglossa, Gray. Teeth in seven series, 3 ■ 1 • 3, the central 

 and inner lateral fixed, the two outer lateral versatile. 



A. Mantle siphoned, enclosed ; mouth of shell channeled in front. 

 Operculum annular or none. 



Fam. XII. CASSIDIDjE. 



Shell subglobose or triangular ; spire short ; siphon of mantle and 

 canal of shell recurved. Operculum ovate or oblong, annular ; nu- 

 cleus elongate in the middle of the inner side, rarely rudimentary or 

 wanting. Teeth 3 ■ 1 ■ 3, the central transverse, many-toothed in 

 front, the inner lateral broad, many-toothed on the inner edge, the 

 two outer lateral subulate, curved, the inner rather shorter, slightly 

 toothed at the top, outer simple. Prehensile collar strong, thick, 

 horny, armed with rows of numerous conic teeth. 



In my former notice of the teeth of Cassis erinaceus, I described 

 the peculiar tooth-bearing collar for the lingual teeth. 



a. Siphon elongate. Mouth of shell elongate, narrow. 

 1. Cassis. 



Shell oblong or subtrigonal ; spire short, nearly flat ; whorls com- 

 pressed, with a varix on each two-thirds of a whorl ; mouth elongate, 

 narrow ; outer lip thickened, toothed within ; inner lip callous, 

 plaited. Operculum oblong, narrow, small ; nucleus subcentral, 

 submarginal. — Adams, Gen. Moll. t. 22. f. 1 b. 



«. Shell subtrigonal. Cassis. 

 1. C. cornutum, Quoy. fy Gaim. Voy. Astrol. t. 45. f. 1. 



j8. Shell oblong ; spire not variced. Cyprsecassis. 



1. C. rufum. 



2. Levenia. 



Shell oblong, ventricose ; spire short, conical ; whorls compressed, 



