MOLLUSC A. 105 



The genus HARP A is well known, and is distinguished by 

 its sharp parallel longitudinal ribs. The pillar is smooth 

 and pointed at the base. 



In the genus EBURNEA, the shell is smooth, and the pil- 

 lar umbilicated and subcanaliculated at the base. The 

 buccinum glabratum is the type of the genus. 



24. STROMBUS. This Linnasan genus is now converted 

 into a family, distinguished by the right margin changing 

 its form with age, and having towards the base an inden- 

 ture or sinus. It contains four gerfera, strombus, rostel- 

 laria, pterocera, and hippocrenis. 



In the genus STROMBUS, the canal is short, the right 

 margin is simple, and ends in a sinus. The S. pugilis of 

 Linnaeus is the type of this genus, 



In the ROSTELLARIA the canal is produced into a long 

 beak, the right edge of the mouth is entire, and rests above 

 on the spire, and is sometimes decurrent. The sinus is con- 

 tiguous to the canal. The R. cornuta of Mart. (Conch, iv. 

 tab. 158. f. 1495,) is the type of the species. 



In the PTEROCERA the canal is also lengthened, but the 

 right margin is dilated and digitated with a sinus near the 

 base. The strombus pes-pelicani of our shores is of this genus. 



25. MUREX. The modern genus of this name is thus de- 

 fined by Lamark : " Testa univalvis, ovata vel oblonga ; 

 basi caniculata ; suturis varicose- tumudis, sub aspens, lon- 

 gitudinalibus, et persistentibus." In consequence of this 

 restriction, the following genera, among others, have bten 

 instituted. 



In the genus FASCIOLARIA, the spires are destitute of 

 those longitudinal ribs which the murices always exhibit, 

 while the pillar is furnished with two or three oblique folds. 

 The murex tulipa of Linnaeus is the type of this genus* 



