A NEW FOSSIL PORPOISE FROM MARYLAND. 171 



Greatest breadth of each premaxilla at same point ^ 



Greatest breadth between premaxillse at base of rostrum 



Distance between proximal ends of premaxillae o 



Greatest breadth of frontal plate of each maxilla external to premaxilla on 



Distance between proximal ends of maxillae „. 



Distance between proximal ends of maxillae and supraoccipital 7 



Greatest thickness of maxilla over orbit 



1 



1 



Greatest breadth of superior nares oo 



Depth of rostrum at base «_ 



Depth of rostrum at middle 2 n 



Length of orbit ~ . 



Length of postorbital process oq 



Length of temporal fossa gny 



Length of zygomatic process from exoccipital r-j 



Least breadth between temporal fossae 131 * 



Height of supraoccipital above foramen magnum ar* 



Breadth of foramen magnum on 



Height of each occipital condyle 3* 



Breadth of each occipital condyle 21 



Length of portion of vomer visible on palate 51 



Distance from last alveolus to maxillary notch 22 



Length of largest superior alveolus 7 



Least distance between alveoli 



Total length of mandible 296 



Length of symphysis 94 



Height of mandible at coronoid process 72 



Height of mandible at middle of length 23 



Height of mandible at posterior end of symphysis 23 



Height of each condyle 22 



Breadth of each condyle 13 



Distance from posterior end of symphysis to last alveolus 86 



Length of largest mandibular alveolus g 



Least distance between alveoli of same side , l 



Distance between alveoli of opposite sides at symphysis 7.5 



Teeth. 

 (Plate XIX, figs. 1 and 2; Plate XXVI.) 



The last three maxillary teeth on the right side, and the last two on the left 

 side are in position (see PI. XVII, fig. 2). Of the mandibular teeth (see PI. XVIII, 

 figs. 2, 3) the last four on the right side are in position, and three others near 

 the middle of the jaw; on the left side, only the penultimate tooth. In addition, 

 numerous detached teeth have been preserved. The dental formula was origi- 

 nally about 2^26- The mandible is almost intact, so that the number of 

 teeth in the lower row can be ascertained with considerable exactness, but the 

 distal end of the rostrum is not sufficiently complete to allow of an accurate 

 count of the upper row. The number above and below, however, is not likely 

 to have differed by more than one or two teeth on each side. 



The teeth are large, relatively, and very close together, and are of extraordi- 

 nary form in that the crowns of the posterior ones are trituberculated, while 

 all the crowns of teeth have more or less strongly developed anterior and posterio 

 longitudinal ridges, and rugose enamel. 



r 



v 



