OF CONCHOLOGY. 141 



Pter. speciosa, d'Orb., P. Dupiniana, cl'Orb., P. marginata, 

 d'Orb. 



Subfamily ROSTELLARIN^E. 



Animal as in Strombince. Operculum small, ovate, not serrate. 

 Shell fusiform or subfusiform, spire usually elevated. 



I have considered it advisable to separate this series of genera 

 as a distinct subfamily, because the characters, though small, 

 are constant, uniting them in a natural group, without close 

 allies beyond its limits. In the two living genera the operculum 

 is characteristic, this member being serrate or denticulate along 

 the margin in the other two subfamilies. 



Genus ROSTELLARIA, Lam. 



Shell fusiform, spire elevated, whorls smooth ; aperture con- 

 tinued into a long straight or slightly curved anterior canal ; 

 outer lip slightly thickened on the margin and denticulated. 



R. fusus, Lam., [Strombus fusus, Linn.) 



The true Rostellarias belong to the present epoch, or extend 

 at most only into the more recent Tertiaries. 



Genus HIPPOCHRENES, Montf. 



Shell fusiform, spire elevated, whorls smooth ; anterior canal 

 long ; posterior canal produced and extending up the spire to 

 near the apex, or curving behind it; labrum expanded, notched 

 above and below. 



H. macroptera, Montf., = Rostellaria macroptera, Lam., IT. 

 ampla, JS. Columbaria. I know of but a single American species 

 — H. extenta = Rost. extenta, Con., of the Eocene of Jackson, 

 Miss. This differs from the typical form in having the outer 

 lip transversely plicate. Essentially an Eocene genus. 



Genus SPINIGERA, d'Orb. 



Shell elongated, slender-fusiform ; anterior canal long and 

 straight ; each volution bearing one or two varices, those of suc- 

 cessive whorls being arranged continuously, as in Ranella, and 

 bearing a long transverse spine. 



In some species these varices occur on only one side of the 

 shell, in others on both sides, as in Ranella, in consequence of 

 which the present form was associated with the genus by Chenu. 



S. longispina, d'Orb., Ranella longispina, Desl. Only, as yet, 

 found in the Oolite. 



