APPENDIX. 621 



Genus MARSENINA, Gray. 



Shell partly external, spiral. 

 One species. 



Genus AMAUROPSIS, Morch. 



(Fam. NATICID.E.) 



Operculum horny, paucispiral, thin. 



Shell longitudinally oval, thin, smooth, white, not umhilicated, 

 covered with a light brown epidermis ; spire elevated, suture 

 canaliculated ; aperture oval, produced in front. 



Ex. A. cornea, Mutter, pi. 137, fig. 5. 



This genus comprises the species, canaUculata, Gould, and 

 cornea, Miiller, which we had included in the genus Amaura. 



Vol. i. p. 219. Genus MORUM. 



A species of this genus has recently been described by Mr. 

 Hanley, under the name of M. ponderosum, possessing so great 

 a peculiarity in the pillar lip as to entitle it to form the type of 

 a distinct group which he suggests might be distinguished as 

 follows. 



Sub-gen. hebculea, Hanley. 



Shell tuberculated ; inner lip sulcated, not granulated. 



Vol. i. p. 220. Genus scala. 

 Sub-gen. acirsa, Morch. 



Shell turreted, thin ; whorls united, varices obsolete ; outer 

 lip thin, simple. S. Eschrichti is an example. 



Vol. i. p. 223. Fam. TEREBRID.E. 



The teeth in this family are said to be similar to those in 

 Conidce, although the mouth, as in Turridce, is without the 

 VOL. II. 4 L 



