[ 117 ] 



3. Mesembrinus, Albers. Ovate-conical, rimate, rather thin, 



striate, white, generally variegated with brown ; aperture 

 oblong-oval, small, lip thin, and not reflected,' eolumellar 

 margin more or less dilated, reflected and appressed, colu- 

 mella slightly twisted. 



4. Thaumastus, Albers. Shell oblong-conical, imperforate 



or rimate, nearly smooth, Avhite, sometimes variegated with 

 brown flames; aperture oblong-oval, lip obtuse, straight or 

 slightly expanded, eolumellar margin reflexed, more or less 

 appressed, columella distinctly twisted. 



5. MoRMUS, Albers. Shell oblong- conical, striate or subcos- 



tate, thin, whitish or variegated with broAvn, upper whorls 

 flattened, the body Avhorl very convex, inflated ; aperture 

 subovate, the lips simple, sharp, eolumellar margin dilated 

 and reflected. 



6. ScuTALUS, Albers. Ovate-conical, perforate or umbilicate, 



roughly striate, whitish or brownish white, seldom varie- 

 gated, last Avliorl ventricose, compressed at the base ; 

 aperture ovate-oblong, peristome more or less expanded, 

 slightly thickened within. 



7. Peronj^us, Albers. Oblong-turrited, perforate, white, some- 



times variegated with brownish, spire elevated, the last 

 whorl one-third of the total length ; aperture oblong-oval, 

 lip expanded, not thickened, eolumellar margin dilated; 

 columella receding or obsoletely arcuate. 



DRYM^US, Albers. 

 1. Drymseus serperastrus, Say. 



Plate 13, figure 4. 



Shell ovate-fusiform, umbilicate, thin, translucent ; spire 

 acuminata, suture moderately impressed ; whorls about 7, a 

 little convex ; aperture elongate-lunate, the lip expanded a 

 little, and reflected upon its eolumellar margin ; umbilicus 

 moderate. Yello-wish white, with about six interrupted bluish 

 black bands on the body Avhorl, which sometimes coalesce ; the 

 internal coloring is the same, except near the lip margin, where 

 the bands disappear. 



Length 37, diam. 17-5 mill. 



Texas and Mexico. 



