124 INVERTEBRATE PALEONTOLOGY. [WHITE. 



proximal side of the next preceding one, but projects a little beyond it so 

 that an angular shoulder is formed upon the proximal side of the suture. 



Aperture subtrihedral in outline. 



Surface marked by the ordinary lines of growth, arid also by numerous 

 minute, raised revolving striae, upon both the outer and anterior sides of 

 the volutions. 



There is considerable variation in the flattening of the outer side of the 

 volutions in different examples and in different parts of the same example. 

 The volutions near the apex of all the shells are usually convex and not 

 much if at all flattened ; in some cases the outer side of the last volution is 

 broadly convex, while in others it is not only flattened- but a little concave, 

 especially the part nearest the suture. 



Length of an average sized example, thirty millimeters; diameter of 

 the last volution, twenty millimeters. 



Genus ODONTOBASIS Meek. 



Odontobasis buccinoidea (sp. nov.). Shell of medium size somewhat 

 robust; volutions six or seven, regularly convex; suture faintly impressed; 

 surface marked by somewhat strong longitudinal folds which end at the 

 suture upon the proximal side of the volutions of the spire, but do not quite 

 reach the suture upon the distal side, and upon the last volution they die 

 out before reaching the anterior end of the shell; the whole surface also 

 marked by somewhat coarse revolving raised lines, which in crossing the 

 longitudinal folds give them a crenulated appearance. The revolving lines 

 upon a narrow space on the proximal side of the suture, and also upon the 

 space in front of the revolving furrow of the columella, are finer than the 

 others. Odontoid process not very prominent, forming a small angular pro- 

 jection at the end of the revolving furrow of the columella. 



Length, thirty-seven millimeters ; diameter of the last volution, twenty- 

 two millimeters; but these proportions vary considerably in different shells 

 of the species. 



Position and locality. Point of Rocks Group; two miles west of Point of 

 Rocks, Wyoming. 



