OF SAjS'TO DOMINGO. 



237 



of indistinct nodes adjoining the suture, and a large number of very fine, closely placed revolving lines covering the 

 entire surface. On the body whorl there is a single obsolete varix. Aperture broad, canal slightly twisted, inner lip 

 without folds, but bearing a tubercle posteriorly. 



About the size and shape of C. fascia tu7n, hut distinguished hj its difFerent surface, 

 by the absence of cohimellar folds and l)y the less deflected canal. 



C. dentilabrum. Gabb, n. s. ' ■ . ' 



Shell large, heavy, spire elevated, sutui-e distinct, whorls flattened on the sides, bearing a few very faint varices. 

 Surface marked by not very strong longitudinal ribs or undulations ; these are crossed by four or five strong revolving- 

 ribs, flat on top and with concave inter.spaces, giving the surface a coarse but pretty regularly cancellate appearance. 

 Aperture sub-quadrate, with two strong folds ou the columella, one in the middle, the other behind ; outer lip with 

 one large tulDercirlar tooth in the middle and one in advance. These folds and teeth are absent in the young shell. 

 Length 2 inches width 0.7 inch. 



Easily distinguished by its coarse cancellated appearance and its dentate mouth. 



C. s u p r a s u 1 c a t u m . Gabl), n. s. 



Shell broad, si^ire moderately elevated, whorls numerous, increasing rapidly in width flat on the sides ; suture chan- 

 neled. Surface plain or marked by a few lines in advance and by a deep revolving groove a short distance below the 

 suture. Aperture sub-quadrate, canal very small, no folds ; outer lip strongly produced on the base, adjoining the 

 canal. Lengtli about 1.5 inch, width .7 inch. 



Easily recognizable by its broad form and its smooth sides with a single groove 

 near the suture. 



C. o b e s u m . Gabb, n. s. 



Shell short, broad, spire about one and a half times as long as the aperture, apical angle very variable, suture 

 linear. Surface very variable. The most usxial character is a series of tubercles near the suture. In some cases 

 these form an angle, in others they are obsolete or entirely wanting while in one specimen they are prolonged into 

 short ribs, with a secondary series adjoining the suture. The entire surface is always covered with minute revolving 

 lines. ^ Aperture sub-ovate, canal very short, not reflexed, a tubercle on the inner lip behind ; outer lip effuse, inter- 

 nally thickened. Length 1. inch, diameter .5 inch. 



The short robust form with rounded outlines of this shell, its revolving thread-like 

 strise and its expanded lip, are unlike any other species I have ever seen. In the 

 great majority of cases it bears a series of small rounded prominences a short dis- 

 tance below the suture. 



C. uniseriale. Sby., Quart. Jour., Vol. VI., p. 51. 



T have studied Sowerby's description of this species carefully and am not certain 

 whether I have been successful in fixing the name to the proper shell. It might 

 apply with some propriety to the immediately preceding species, but seems to agree 

 more nearly with the one before me. This is much more slender, with an elongated 

 spire, bearing a series of small tubercles on the angle, and crossed by pretty strong, 

 and somewhat alternated revolving lines. The canal is elongate, moderately twisted, 

 with the ordinary terminal fold and with a posterior tubercle. Length about one 

 inch. 



A. p. s. — VOL. XV. 3h. 



