100 STKOMBID^. 



Differs from Strombinse in the form and adaptation of the 

 foot a/id in the dentition; the shell differs in the absence (in 

 most of the genera) of a labial sinus, but is closely related with 

 the Pterocera of the Strombiriae, and a little remotely with the 

 Cerithiidee. 



Subfamily STRUTHIOLARIINVE. Tentacles slender, rather short, 

 with the eyes on short pedicels at their external bases ; foot 

 oval, adapted for swimming ; proboscis long ; siphon scarcely 

 perceptible. Operculum shortly unguiculate. Dentition: 5*1'1'1'5; 

 central tooth subquadrangular, with multicuspid edge, the 

 laterals oblong, multicuspid; marginals falciform, sharp, narrow, 

 with crenulated margins (PI. 12, fig. 42). 



Shell bucciniform, the aperture angular, shortly subcanalicu- 

 lated below; lip thickened, sinuous, entire; columella thickened, 

 polished, subtruncate below. 



Synopsis of Genera. 



The Strombidre abound in fossil forms, some of them of very 

 bizarre appearance ; as these are all described and illustrated in 

 the " Structural and Systematic Conchology," they will be 

 simply named here, with references to that work. 



Subfamily Strombinfr. 

 Genus STROMBUS, Linn.. 1758. 



Shell ovate, turreted or subfusiform, often tuberculated or 

 spinose, imperforate, covered by a thin, horny epidermis, solid ; 

 aperture long, narrow, emarginate or with a short canal in front, 

 ctinaliculated or channeled posteriorly ; outer lip usually dilated, 

 thickened, often lobed, with a sinus near the front ; columellar 

 lip simple, callous. Operculum narrowly unguiculate, the margins 

 denticulated, or rugose. In the young, the lip of the shell is 

 not expanded, so that it appears something like a Conus. 



Section I. STROMBUS (sensu stricto). Lip with entire margin, 

 widely expanded, not prolonged upon the spire behind ; inner 

 lip not restricted or defined. S. yigas, Linn. 



Section II. EUPROTOMUS, Gill, em., 1869. Lip widely expanded, 

 ascending the spire, the outer margin folded in and thickened, 

 the posterior margin ^ubdigitate or plain. 6'- lavimatus$< Chemn. 



