320 



CERITHIID.E. 



Fig. 589. 



Aporrhais occidentalis. 



Fig. 205. 



Shell spindle-shaped, the outer lip expanded into a broad, thick wing ; whorls 

 convex, with numerous waving, longitudinal folds, and regular, conspicuous, re- 

 volvnig lines. 



Rostellaria (Aponhais) occidentalis. Beck, Lyell's Catal. of Fossils of St. Lawrence Bay, 

 in Geolog. Trans. — Guerin, Mag. de Zool. May, 1836, pi. 72. — De Kay, N. Y. 

 Moll. 155, pi. 8, tig. 177. — Gould, Inv. 1st ed. 298, fig. 205. 



Aporrluiis occidtntulis, .Soweruy, Thes. 21, pi. 5, fig. 2. — Reeve, Conch. Syst. ii. 202, 

 pi. 246, tig. 3. — Stimpsox, Check Lists, 5. 



Chenopus occidentalis, Ciienu, Man. i. 262, fig. 1647. — Lamarck, An. sans Vert. iv. 658. 



Shell thick but light, of a livid or bluish-white color ; excluding 

 the wing, it is spindle-shaped, composed of eight or nine moderately 



convex whorls, witli numerous smooth, 

 rounded, crescent-shaped folds, which 

 scarcely reach the well-marked sutures ; 

 on the largest whorl there are about 

 twentj^-five folds, and on the last but 

 one they become closer and fainter, till 

 they finally disappear on the back ; two 

 or three whorls at the pointed apex are 

 also destitute of folds ; beautiful revolv- 

 ing lines, of uniform size and distance, 

 also ornament the shell ; aperture cres- 

 cent-shaped, independent of the wing ; 

 this arises a little above the suture of 

 the preceding whorl, and passes off from 

 the spire at an angle of aljout one hun- 

 dred and twenty degrees, to a distance 

 equal to the breadth of the lower whorl ; 

 after forming somewhat of a spur at the posterior and outer angle, 

 it advances, smooth, and very thick, at nearly a right angle, in a 

 straight line nearly an inch, then, forming an ol:)tuse angle, passes 

 obliquely forward to the pointed termination of the columella, form- 

 ing with it a short, shallow, and oblique canal ; ])illar lip smooth 

 and rounded, convex above, and concave below ; tliroat livid ; a 

 thick, dusky epidermis. Length, two and one fourth inches ; breadth, 

 one and a half inches ; divergence, forty degrees. 



Tips of this shell, some of them, liowevcr, wanting nothing but the 

 expansion of the lip, are all that have yet been found in our Bay, 



A. occidentalis. 



