NASSID.-K. 7 



SiibfjenuK Hebra, H.aiid A . Atlains. Wlioilsspiiiosp/ninriratpd or shari'l.V 

 tubercular; inner lip with the callus ileliued ; outer lii> with a nuir<^iii:il 

 varix, when adult. 



Subgenus Hima, Leach. Spire elevated, whorls c.uicellated ; inner lip 

 with a rugose callus, callus defined ; outer lii> with a marginal varix. 



Subgenus Niotha, H. and A. Adams. Shell cassidiform ; spire short, 

 whorls granulated or cancellated ; inner lip with the callus very large 

 and spreading ; outer lip crenate, not variced externally. 



Subgenus Tritia, Risso. Spire elevated, whorls reticulated ; inner lip 

 smooth, with the callus moderate; outer lip simple, not variced.- 



Subgenus Ilyanassa, Stimpson. Shell dark olive brown, reticulated, 

 outer lip without varix, striate within, columella covered with a 

 spreading callus. Operculum with entire (not serrated) margin. 

 Animal having a broad foot, not bifurcated behind as in Nassa. Den- 

 tition, PI. 3, fig. 25. 



NERITULA, Plaucus. Shell ovate, depressed, axis distorted ; spire 

 flattened, oblique, whorls smooth ; aperture depressed ; columella 

 smooth ; inner lip callous, spread over the body whorl, outer lip reflected, 

 not denticulate or striated. Dentition, PI. 3, fig. 26. 



DESMOULEA, Gray. Shell ovate-globose, covered with a downy 

 epidermis ; spire short, conical, apex papillary ; whoi'ls depres-ed ; 

 aperture ovate ; inner lip thickened, with a ridge posteriorly ; outer 

 lip contracted, thickened externally, plicated internally. Dentition 

 unknown. 



Fossil Oenera and Subgenera. 



Subgenus Molopophorus, Gabb. (S. G. of BuUia). Short, robust, 

 spire moderately elevated, suture bordered by a more or less distinct 

 carina. Surface longitvidinally ribbed or striate. Aperture obtuse behintl, 

 and very slightly notohed ; outer lip simple, inner lip very slightly in- 

 crusted, sivmous, anterior notch small, but distinctly defined. 

 B. striata, Gabb. PI. 3, fig. 27. Cretaceous, Calif ornin. 



Genus PTYCHOSALPINX, Gill. Shell ovate, buccinoid, whorls regu- 

 larly rounded and ventricose ; spire moderate (about as long as the 

 aperture), furnished with equal revolving linear ridges, siphonal canal 

 very short, very obliquely twisted and concurrent with the siphonal 



"•■■ H. and A. Adams have also a subgenvis JJzita, but its characters are 

 not difi^erent from those of Tritia, whilst its species ai-e, many of them, 

 evidently better placed in other groups : a large number of them, for 

 instance, possess the marginal varix, the absence of which is one of the 

 characters of the group. IJzita can be advantageously dispensed with. 



