from the Gulf of California, etc. 379 
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 (Pl. 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 ; columellá vix plicatá. 
Shell lanceolate ovate, very thin, smooth and glistening, pale 
horn color, colorless at suture ; spire acute ; whorls nearly six, dis- 
tinet, 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. ; 
SIGARETUS DEBILIS (Pl XIV. Fig. 17.) 
T. parva, tenuis, lucida, depressa, mellea, striis numerosissimis obtusis vol- 
Ventibus, supernis majoribus, insculpta; spira superficiei generali congruens; 
anfr, duobus; apice ad quadrantem diametris sito: angulo ad peripheriam 
obtuso, versus aperturam sensim evanido ; labio anticé 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 
obtüse-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, 
