BULIMULUS. 



391 



Fig. 274. 



marked with spots and obsolete blotches of horn-color; spire conic, acute; 

 whorls 6 1, rather convex, the last about as long as the spire, hardly attenuated 

 at base; columella with a small dentiform fold; aperture scarcely oblique, 

 acuminately oblong, brownish within; peristome straight, its 

 right margin somewhat arched, its columellar margin broad- 

 ened above, spreading. Length 33, diameter 14-15 mill.; of 

 aperture, length 16-17, breadth 7^ mill. 



One of the uniformly white forms of the species is figured 

 in Fig. 274, and two of the same from the table-land west of 

 Fort Clark, figured in Fig. 272, show the variation in breadth 



of which the species is capable. 



Jaw as usual in the genus ; nu- 

 merous delicate ribs ; a strong upper 

 muscular attachment. 



There are about 76 rows of teeth on the lingual 

 membrane of B. alternatus, each consisting of 75 

 (37 1 37) teeth. Central teeth long, unicuspid, 

 bluntly pointed, the laterals bicuspid, modified as 

 they pass off laterally into the marginals. 

 Genitalia not observed. 



Bulimulus Schiedeanus, PFEIFFER. 



Fig. 275. 



B. alternatus. 



Lingual dentition of 

 B. alternatus. 



Fig. 276. 



B. Schifileanus. 



Shell perforated, ovate-acute, calcareous, white, with irregular longitudinal 

 wrinkle-like striae ; whorls 6^, rather 

 convex, the last as long as the spire ; 

 aperture oval-oblong, brownish within ; 

 columella obsoletely folded ; peristome 

 simple, acute, its margins joined with 

 a shining callus, the columellar one 

 broadly reflected, white and shining. 

 Length 31, diameter 17 mill. ; length 

 of aperture 1 7, breadth 9 mill. 



Bulimus Schiedeanus, PFEIFFER, Symb. ad Hel. Hist., I. 43 ; Mon. Hcl. Viv., 1 

 II. 187; in CHEMNITZ, ed. 2, No. 216, PI. XLVI. Figs. 3, 4 (1854). Pin- 

 LIPPI, Icon., I. 3, p. 56, PI. I. Fig. 12 (1843). REEVE, Con. Icon., No. 361. 

 - W. G. BINNEY, Terr. Moll., IV. 129 ; L. & Fr.-W. Sh., I. 204 (1869). 



Bulimus alternatus, BINNEY, Terr. Moll., PI. LI. Fig. 2. Not of SAY. 



Thaumastus Schiedeanus, TRYON, Am. Journ. Conch., III. 172 (1867). 



Texas and the neighboring part of Mexico. Very common in Washington 

 County, Texas. 

 From Bulimulus alternatus this species is distinguished by a rougher surface, 



i Pfeiffer quotes also as synonymes the manuscript names E. xanthostomus, Wiegm., 

 and B. candidissimus, Nyst. 



