MANGELIA. 451 



gracefully adorned with prominent and sharply pronounced 

 narrow longitudinal ribs, or riblets, which are rather dis- 

 tant (at least are not so broad as their intervals) almost 

 perpendicular, and, except perhaps about the angle, are not 

 at all flexuous ; they continue in full strength to the base of 

 the smaller turns, but dwindle away upon the anterior part 

 of the body- whorl, where they finally cease before the com- 

 mencement of the caudal portion. Both ribs and intervals 

 are alike crossed by numerous closely disposed spiral cos- 

 tellar lines, that are not much elevated, and are of rather 

 irregular thickness. The whorls are peculiarly scalar, rising 

 perpendicularly from the fine and simple suture, and being 

 more or less abruptly and horizontally angulately flattened 

 at their upper extremity ; they are short, and of gradual lon- 

 gitudinal increase. The less abrupt is the scalar structure, 

 the finer and less prominent are the ribs and stria3. The 

 spire, which is composed of six or seven rather flat-surfaced 

 turns, does not exceed the body in length, and tapers rather 

 quickly to a fine point. The body which occupies about 

 one half of the entire length, is rather quickly attenuated 

 from the broad posterior extremity so as to form a right 

 angled triangle ; the base is a little produced. The narrow 

 aperture is nearly as long as the spire above it ; it is 

 produced anteriorly into a rather broad and not much 

 elongated canal, which bends up slightly at its extremity. 

 The outer lip is acute, simple, and more or less angular in 

 outline. The inner lip is subangulately incurved above, 

 and straight below ; the enamel is much spread on the 

 columella, which is produced, and devoid of all sculpture. 

 Fine examples measure three-quarters of an inch long, 

 with a diameter of nearly the third of an inch. 



A kind of spiral ridge frequently subtuberculates the 

 ribs at the angle of the whorls. 



