220 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



under the peristome of the shell ; generative orifice behind the right eye- 

 peduncle ; no caudal mucus pore or locomotive disk. 



Shell rimate, cylindrical or oblong-ovate, perpendicularly costulate or ribbed, 

 solid, white, often variegated with red ; whorls 9-12, the last narrowed to- 

 wards the base, often ascending ; aperture semi-oval, usually bluish-brown 

 within ; columella with a dentiform fold, parietal wall furnished with an in- 

 ternal denticle ; peristome thickened, reflexed, its margins connected by a 

 somewhat heavy callus. 



A West-Indian genus, found also in the Florida Subregion. 

 But one species, S. incana, Binn., is found within our limits. I have found 

 it to agree in the characters of its jaw and lingual membrane with the ex- 

 tralimital species which I have examined, S. iostoma, mumia, 

 and decumana. Semper, however (Phil. Arch. 128), describes 

 the jaw of S. uva as being without median projection to its 



cutting edge : that character, therefore, cannot be considered 

 Jaw of S. incana. 



generic. 



Jaw of S. incana (Fig. 125) arcuate, thick, coarse, of about equal height to 

 its bluntly truncated ends ; cutting edge with a slightly produced median pro- 

 jection. Anterior surface without ribs. 



Lingual membrane arranged as in Patula (see PI. V. Fig. A) with 27 1 27 

 teeth. The change from laterals to marginals is as shown in the ninth and 

 tenth tooth. There is the usual splitting of the inner cutting point beyond the 

 ninth tooth. The extreme marginals are low, wide, with one inner, long, 

 bluntly bifid cutting point and one outer, short. All the changes from centrals 

 to extreme marginals are shown in the figures. 



The splitting of the inner cutting point of the marginals was not detected by 

 me before in S. iostoma and rnumia. I have, however, lately found it in those 

 species. 



Strophia incana, BINNEY. 

 Vol. III. PI. LXVm. 



Shell deeply rimate, cylindrically oblong, solid, smooth or delicately striate, 

 shining, chalky ; spire elongate, gradually attenuated into a rather acute cone ; 

 suture light, margined; whorls 11, flat, very gradually increasing, the last 

 scarcely equalling or shorter than the length, wrinkled anteriorly, more or less 

 arcuately ascending, at base subcompressed ; aperture small, roundly lunate, 

 light flesh-color within, furnished with a moderate deeply seated parietal tooth 

 and an obsolete columellar fold ; peristome somewhat thickened, shortly re- 

 flected all round, its terminations joined by a thin callus, that of the columella 

 dilated and arched above. Length, 26 mill.; diameter, 10 mill.; of aperture, 

 length, 8-9 mill. ; diameter, 7-8 mill. 



A variety has irregular longitudinal streaks of reddish-brown. (Fig. 126.) 



