EASTERN PROVINCE— SOUTHERN REGION SPECIES. 419 



foniul it to agree in the characters of its jaw and lingual membrane ^ itli 

 the extialiraital species which I have examined, S. iostoma, -'^^Hi^-- 

 mumia, and decumana. Semper, however (Phil. Arch., 

 128), describes the jaw of -8. uva as being without median jawocs. « 

 projection to its cutting edge; that character, therefore, cannot be 

 considered generic. 



Jaw of S. incana (Fig. 462) arcuate, thick, coarse, of about equal 

 height to its bluntly truncated ends; cutting edge with a slightly 

 produced median projection ; anterior surface without ribs. 



Lingual membrane arranged as iu Fatula (see Terr. Moll., V, Plate Y, 

 Fig. A, and Fig. 4G3), with 27-1-27 teeth.' The change from laterals to 

 marginals is as shown in the ninth and ^i«- ^^s. 



tenth t«^eth. There is the usual splitting ^i;^ ^ c^c^ ST^'CT^? 

 of the inner cutting point beyond the ^r %X ^^W^ ^^ftA 

 ninth tooth. The extreme marginals are Lingual dentition of s. incana. 

 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. iosioma and mumia. I 

 have, however, lately found it in those species. 



Atrophia incana, Binney. 



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

 striate, shining, chalky; spire elongate, gradually atten- ri«-4G4. 

 uated into a rather acute cone ; suture light, margined : 

 whorls 11, flat, very gradually increasing, the last scarcely 

 equaling or shorter than the length, wrinkled anteriorly, 

 more or less arcuately ascending, at base subcompressed ; 

 aperture small, i^oundly lunate, light flesh-color within, 

 furnished with a moderate, deeply seated j^arietal tooth 

 and an obsolete columellar fold ; peristome somewhat . g, incana. 

 thickened, shortly reflected all round, its terminations joined by a tliin 

 callus, that of the columella dilated and arched above, i.ength, 26""" ; 

 diameter, 10""". Of aperture : Length, 8-9"™; diameter, 7-8™™. 



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

 465). 



Pupa incana, Binney, Terr. Moll., i, 109 ; iii, pi. Ixviii.— Leidy, T. M. U. S., i, pi, xv, 

 tigs. "2-4, anat.— Pfeiffer, Mai. Bliitt., ii, 13 ; Mou. Hel. Viv., iv, 657.— W. 

 G. BiNNKY, Terr. Moll., iv, 140, pi. lxxix,fig. 17; L. & Fv.-W. Sli., i, 247, 

 fig.*430 (18G9).— Tryon, Amer. Journ. Conch., iii, 308 (1868). 



