138 AMERICAN JOURNAL 



within the last few years, since the tendency to close generic 

 division has become more universal than formerly. 



The same reasons which have caused one author to call a shell 

 a Rostellaria, and another to place it in Aporrhais, while it per- 

 haps really belongs to neither, have rendered the determination 

 of the family relation of some of the genera extremely doubtful. 

 I refer to the comparatively little dependence that can be placed 

 on the shell character in some instances, among the extinct 

 winged forms ; a difficulty to which is superadded the impossibility 

 of settling the question by a study of the animal. 



Family STROMBID^E. 



Lingual membrane with seven rows of teeth (3 — 1 — 3) the 

 central teeth single ; the lateral three on each side, the inner one 

 tri-dentate, the outer simple or uncinate. Muzzle elongate, 

 tapering ; eyes at the extremity of long robust peduncles ; ten- 

 tacles, when present, arising from the middle of the eye pedun- 

 cles ; mantle with the outer side generally expanded and often 

 lobed ; foot narrow, compressed, dilated in front and tapering 

 behind. Operculum ovate and simple or claw-like and serrated. 

 Shell ovate, turrited, fusiform or subulate ; in most genera the 

 outer lip changes in the adult and becomes heavier, digitated or 

 notched. 



Sub-family STROMBINJE. 



Tentacles on the middle of the eye peduncle ; foot with the 

 hind part narrow, subcylindrical, elongated. Shell with the 

 outer lip more or less expanded and notched towards the fore 

 part. Operculum unguiculate, margin serrated. 



Genus STROMBUS, Linn. 



Outer edge of mantle entire. Operculum unguiculate, margin 

 serrated. Shell ovate, turrited or sub-fusiform ; aperture 

 narrow, elongate, emarginate or with a short canal in front, 

 canaliculated posteriorly ; outer lip often lobed and with a deep 

 notch in front near the canal. 



S. vittatus, Linn. 



H. and A. Adams propose three subgenera besides the more 

 typical forms of the genus, as follows : — 



Monodactvlus, (Klein), H. and A. Adams. Outer lip with a 

 lobe at the posterior part much produced. S. adustus. 



