32 PROCEEDINGS OP THE NATIONAL MUSEUM mgl, «:'•. 



it merges into the groove leading forward from the foramen at the 

 level of the posterior end of the symphysis. 



The conformation of the proximal end of the right mandible is. 

 similar to that of Sotalia tucucoi, except that the angle is prolonged 

 farther backward and the posterior margin of the ramus above the 

 angle is more strongly curved. The coronoid region is not especially 

 elevated, the distance between the apex of the coronoid process and 

 the inferior margin of the angle amounting to less than one- fourth, 

 of the total length of the mandible. The superior margin of the 

 mandible slopes from the coronoid process to the middle of the tooth 

 row, while the inferior margin is convex behind the end of the tooth 

 row. The external face of the proximal end of the mandible is 

 convex, except that the superior border of the coronoid process is 

 bent outward as in Sotalia tucuxi. Although the right mandible is 

 distorted from crushing, the angle appears to have extended back- 

 ward nearly to the level of the condyle. The condyle is elliptical in 

 outline, with the long axis oblique. 



Back of the tooth row and on the internal surface of the ramus 

 there is the usual orifice for the large dental canal. Beyond this 

 orifice the ramus consists mainly of the thin outer shell, with the 

 addition of shelving strips which merge into the upper and lower 

 borders. 



Measurements of the right mandible {in millimeters) 



Cat. No. 

 8060 



Greatest length of right mandible (condyle to tip) 262 



Greatest breadth of combined mandibles at extremity 10 



Greatest depth of combined mandibles at extremity 10 



Greatest depth of right mandible at proximal end of symphysis 15. 8 



Greatest depth of right mandible at level of proximal alveolus 31 



Greatest length of symphysis 85 



Distance from proximal alveolus to distal alveolus 161 -|- 



Depth of condyle of right mandible 18 



TEETH 



With the exception of the distal ones, practically all of the teeth 

 are in position on the left side of the rostrum and on the left 

 mandible. Behind the greatly enlarged anterior tooth at least five 

 teeth are missing near the extremity on the right side of the rostrum 

 and more than half of the teeth are missing on the right mandible. 

 In addition, seven detached teeth have been preserved. The dental 

 formula was originally about 40 — 40. 



38—38 

 The teeth (pi. 4) are small, very close together, and have slender 

 crowns, the apices of which are recurved. These teeth are quite 

 unlike those that have been described previously from the Calvert 



