266 STROPHOSTOMA. 



STORILLUS. Montf. 1, 131. A genus of microscopic Foraminifera, 

 included in the genus Rotalites in M. De Blainville's system. 



STRAPAROLLUS. Mont. A genus containing some species of 

 Helix, Auct. Generic characters not defined. 



STREPTAXIS. Gray. Fam. Colimacea, Lam.— Descr. Ovate, or 

 oblong ; when young, sub-hemispherical, deeply umbilicated, with 

 rapidly enlarging whorls. At length the penultimate whorl is 

 bent towards the right and dorsal side of the axis, and the 

 umbilicus becomes depressed, and often nearly closed. The 

 mouth is lunulate, the edge slightly thickened and reflected, and 

 often with a single tooth on the outer side of the inner lip. — 

 Obs. This genus of land shells is separated from Helix on account 

 of the eccentricity of the penultimate whorl. S. contusa, fig. 269. 



STRIATED. (Stria, a groove.) Marked with fine grooves or lines. 



STRIGOCEPHALUS. Defr. Pentamerus, Sow. ? Gypidia, Pal- 

 man. 



STROMBUS. Auct. Fam. Alatse, Lam. Angiostomata, Bl. — Descr. 

 Oblong, turrited, rather ventricose, solid ; aperture generally 

 lengthened, terminating posteriorly in a short canal, and anteri- 

 orly in an emargination or truncated canal ; outer lip, when 

 young, thin, ; when full grown, thickened and expanded, lobed 

 at the spiral extremity, sinuated anteriorly near the caudal canal. 

 — Obs. This well known genus includes some species of immense 

 size, commonly called conch shells. Most of the recent species 

 are brought from the Indian Ocean. Very few fossil species are 

 known. The young shells have very much the appearance of 

 cones, the outer lips being thin. There are also several species 

 which do not, even when full grown, thicken their outer lips very 

 considerably. The genus Strombus is distinguished from Ros- 

 tellaria, by the notch in the outer lip, which in the latter genus is 

 close to the canal. Fig. 406, S. pugilis. 



STROPHOMENA. Rafinesque. Orthis, Dalman. 



STROPHOSTOMA. Deshayes. A fossil shell, of the family of 

 Colimacea, Lam. in some degree resembling Anostoma, having 

 the aperture turned upwards towards the spire, it is, however, 

 umbilicated, and is said to have an operculum resembling 



