MIOCENE PORPOISES — KELLOGG 139 



possess a small tubercle above the base of the crown on the posterior 

 basal angle. One tooth (pi. 16, figs. 3, 7) has, in addition, a very 

 small cusp above the basal cusp on the posterior face. With the ex- 

 ception of the elongated anterior teeth the outer face of the enamel 

 crown of most of the teeth is lightly sculptured near the base. Four 

 teeth have a faint carina on the outer face extending from the base 

 toward the apex of the crown. On most of the teeth, however, the 

 enamel on the crown above the lightly ornamented basal portion is 

 relatively smooth (pi. 16, fig. 7). The ratio of the height of the 

 enamel crown varies considerably, being equivalent to less than 18 

 percent of the length of the longest tooth and to less than 28 percent 

 of the shortest tooth. 



The roots of the two elongated teeth (pi. 16, fig. 5) are nearly 

 straight, while those of the other teeth are more or less curved. The 

 roots of the posterior teeth are expanded below the crown and taper 

 toward the extremity. The swelling is most noticeable on the upper 

 third of the root (pi. 16, fig. 3) of six of the teeth and on the upper half 

 of the others (pi. 16, fig. 2). Most of the roots are compressed from 

 side to side near the extremity. The elongated teeth were implanted 

 presumably at the extremity of the rostrum, since similarly elongated 

 teeth have been recorded for Kentriodon pernix (Kellogg, 1927, pi. 8, 



fig. 1). 



Among the unfigured teeth there are four that exhibit deviations 

 from those described above. Under visual examination the enamel 

 on the crowns of these teeth appears to be rather smooth, but when 

 magnified 4 to 10 times the ornamentation described below can be 

 seen. 



One complete tooth, 34 mm. in length, has the basal 3 mm. of the 

 enamel on the circumference of the crown wrinkled or more precisely 

 ornamented with low tonguelike projections extending more or less 

 vertically from the basal margin, as well as a faint vertical carina on 

 the posterior side of the internal face, and a similar carina on the 

 anterior side of the external face. This ornamentation of the enamel 

 around the basal circumference of the crown is similar to that of the 

 teeth in the left mandible (pi. 16, figs. 9, 10). 



Another essentially complete tooth, 31.5 mm. in length, although 

 worn on the posterior face, has a similar but less well developed orna- 

 mentation on the circumference of the base of the crown, in addition 

 to a number of fine irregular vertical carinae spaced approximately 

 2 to 3 mm. from one another on all sides of the preserved portion of the 

 crown. 



A somewhat longer tooth, 37 mm. in length and lacking the posterior 

 half of the crown, has a carina on the anterior edge of the internal face 

 and a faint oblique carina on the anterior face in addition to short 



