agrees with the description of B. infrequens, C. B. Adams, and I 

 should not presume to consider it different, had it not been examined 

 by Prof. Adams himself. 



PHYSA ELATA (PI. XIV. Fig. 4.) 



T. tenuissima, ovato-lanceolata, levigata, nitida, dilute cornea, ad suturam 

 decolorata ; spira acuta, anfr. sex, convexiusculis, ultimo octantes septem longi- 

 tudinis equante, antice angustato ; apertura angusta, trientes duos long, ade- 

 quans ; columella vix plicata. 



Shell lanceolate ovate, very thin, smooth and glistening, pale 

 horn color, colorless at suture ; spire acute ; whorls nearly six, dis- 

 tinct, slightly convex, the last one seven eighths the length of the 

 shell, ellipsoidal, nearly symmetrical at the ends ; aperture three 

 fourths the length of the shell, narrow obovate-lunate, acutely 

 rounded anteriorly ; having on the pillar an imperfect fold, and a 

 very thin callus on the body whorl. 



Length seven eighths of an inch ; breadth three eighths of an inch ; 

 length of aperture five eighths of an inch. 



Inhabits Lower California. Maj. Rich. 



An elongated species almost as slender as P. hypnorum, though 

 very much larger, highly polished, with a very long aperture ; pil- 

 lar region tumid. 



SIGAEETUS DEBILIS (PL XIV. Fig. 17.) 



T. parva, tenuis, lucida, depressa, mellea, striis numerosissimis obtusis vol- 

 ventibus, supernis majoribus, insculpta ; spira superficiei general! congruens ; 

 anfr. duobus ; apice ad quadrantem diametris sito : angulo ad peripheriam 

 obtuso, versus aperturam sensim evanido ; labio antice dilatato. 



Shell small, much depressed, thin, almost pellucid, pale honey- 

 yellow color ; whorls two, spire almost coincident with the general 

 surface, apex at one fourth the diameter of the shell ; periphery 

 obtuse-angular, becoming more so as it approaches the aperture ; 

 ventral surface excavated at the umbilical region, with a slight 

 unappressed lamina at that point ; margin of the aperture having a 

 very slight advance in the outline, as it approaches the peripheral 

 angle ; surface with very numerous and very delicate, obtusely 

 excavated revolving striae, much finer on the ventral than on the 

 dorsal face. 



