316 Monograph of the Gasteropoda. 



volutions ; aperture elongate-ovate, or elliptical, produced below, 

 forming a subrimate canal ; columella slightly twisted, without folds ; 

 peristome sharp ; surface smooth. 



The shells have the general form of Fusvs, and particularly the group 

 Tritonofums of Beck ; being smooth shells Avith subequal extremities, 

 but the columella is much less twisted, which gives to them a more 

 erect aspect. They differ from SuhuUtes in not being truncate at the 

 base of the columella, and in being destitute of the deep basal notch 

 characteristic of that genus. 



Types, Fusispira ventricosus and F. terehriformis. 



Fusispira terehriformis — (Hall, 1871). 



Shell terete, acute (subfusiform) consisting of about six, gradually 

 increasing, depressed convex volutions, the last one of which forms 

 about two fifths of the entire length of the shell, exclusive of the 

 anterior prolongation ; aperture narrow, obliquely elliptical, strongly 

 modified above by the preceding volution, and prolonged below, form- 

 ing an extended canal ; surface apparently smooth ; apical angle about 

 thirty degrees. 



This species is found at the quarries back of Cincinnati, though good 

 specimens are very rare. Its range is not known. 



Fusisp ira su bfus iformis — (Hall) . 



Fusiform, elongated ; spire rapidly ascending ; volutions about six 

 or more, flattened, lower one large and veutricose ; aperture oval, 

 acutely extended below ; surface unknown. 



All the specimens yet discovered are casts, which preserve no part 

 of the shell or external markings. It is readily distinguished from 

 F. terehriformis, by the greater obliquity of the volutions, which are 

 flattened, and never present the regular convex outline of that species. 



The specimens referred to this species are quite rare, and have been 

 found in the lower part of the Cincinnati Group. 



Genus Pleurotomaria — (Defrance). 



\_Etym. — Pleura, side, and tome, notch.] 



Shell, trochiform, solid, few whorled, with the surface variously 

 ornamented ; aperture subquadrate, with a deep slit in its outer margin. 

 The part of the slit, which has been progressively filled up, forms a 

 band round the whorls. 



