ART. 14. MARYLAND FOSSIL PORPOISE KELLOGG. 25 



angle is abruptly truncated. The condyle is large, flattened, and 

 slopes obliquely backward ; the external margin projects laterally be- 

 yond the plane of the coronoid. 



When viewed from the ventral side (pi. 3) the symphysial region 

 is seen to be much broader than that of Lipotes. A pair of longi- 

 tudinal grooves incloses a raised ridge which diminishes in 

 height and in width anteriorly. Eight or more foramina open into 

 each of these grooves. The grooves extend forward to the tip of 

 the symphysis, but on the distal 75 mm. they are reduced to very 

 narrow channels. Posteriorly, they extend backward a short dis- 

 tance beyond the symphysis. 



Measurements of the mandibles. 



mm. 



Length of right mandible (condyle to tip) 1,097.0 



Length of left mandible (condyle to tip) 1, 120. 



Greatest breadth of combined mandibles at extremity 18. 



Greatest depth of combined mandibles at extremity 9. 3 



Greatest breadth of combined mandibles at proximal end of symphysis- 90. 



Greatest depth of combined mandibles at proximal end of symphysis — 27. 



Greatest depth of right mandible at level of proximal alveolus 21. 5 



Greatest depth of left mandible at level of proximal alveolus 21. 7 



Greatest length of ankylosed symphysial portion of ramus 803. 



Length of right alveolar row 820.0 



Length of left alveolar row 845.0 



Depth of mandible at coronoid (estimated) 135.0 



Depth of condyle of left mandible 45. 



The anteriormost pair of teeth on the rostrum is considerably 

 larger than any of the following teeth, but the form of the crown and 

 the character of the enamel are essentially the same in all of the 

 teeth preserved. Nineteen teeth are in place on the right side of the 

 rostrum. Of the mandibular teeth 13 are in place on the right side 

 and 12 on the left side. The alveoli are distinct and anteriorly are 

 arranged in pairs. The alveoli number 87 on the right side and 8G 

 on the left side of the rostrum; 70 alveoli are present on the right 

 and 72 on the left mandible. 



The total number of teeth present originally was about 315, of 

 which 45 or about one-ninth are preserved. This fossil skull possessed 

 more than twice as many teeth as an average Platanista skull ; the 

 anterior teeth are relatively shorter than the same teeth of Platanista 

 and all project strongly beyond the sides of the rostrum and lower 

 jaws. The teeth of Lipotes project to some extent beyond the sides 

 of the rostrum and mandibles, more so than in Inia., but not so 

 strongly as in this fossil skull. The anterior teeth of this fossil skull 

 are noticeably larger and longer than the posterior teeth. The second 



