<'ope.] 14^ [^jlay 15, 



fossse approach near together on the median line, forming a short sagit- 

 tal crest, which is about as wide as it is long. From this the temporal 

 ridges diverge abruptly, and these extend in a nearly straight line for- 

 wards, diverging from the line of the axis of the skull at an angle of 

 about twenty-five degrees. Between it and the lateral occipital crest 

 the temporal fossa is concave to the line of the anterior border of the 

 squamosal bone. At the latter point the line of the suture presents an 

 angle, which extends downwards, outwards and forwards. Between 

 it and the posterior temporal crest the surface is concave above. 



The exoccipital is flat vertically, and extends a little posterior to the 

 transverse line of the occipital condyles. The postglenoid face of the 

 squamosal is vertical, and it projects laterally beyond the exoccipital. 

 The postglenoid crest is not conspicuous, and the glenoid cavity presents 

 downwards, and very little forwards. The posterior temporal crest 

 bounds a groove of the superior face of the part of the squamosal that lies 

 posterior to it. The latter face is quite wide, and its external bounding 

 angle is a right angle. It is continued as the superior face of the zj'go- 

 matic process. 



The petrous bone has a peculiar form. Its mastoid portion presents 

 externally a nearly discoid outline between the exoccipital and squam- 

 osal. Its inferior portion descends as a process which forms the short 

 stem of a half-tubular horizontal portion, which opens dowuAvards 

 and posteriorly, forming a partial meatus auditorius. 



The lateral descending borders of the basioccipital are so prominent 

 as to enclose a deep groove between them. The posterior nares are 

 about opposite to the anterior border of the foramen lacerum. 



The frontal region at its posterior apex is convex from side to side. 

 As it widens it presents three subequal faces, two lateral and one 

 median. The median plane is separated from the laterals by a shallow 

 groove on each side, which become deeper anteriorly, and turn abruptly 

 outwards at tlie nareal border. They appear to be the outlines of the 

 nasal bones. Anteriorly the lateral planes become thickened longitudi- 

 nally just external to these grooves. The entire anterior portion of the 

 external planes is a sutural surface, with longitudinal grooves for a 

 length averaging 40 mm. This surface can relate to nothing but the 

 premaxillary and maxillary elements. This point of attachment is, how- 

 ever, anterior to that of any known genus of Mj'sticete ; and is anterior 

 to that in tlie Agoropliius pygmceus Miill. In not extending so far pos- 

 teriorly as the nasal bones, it leaves the frontals to embrace the latter 

 anteriorly to an unusual extent. This is on the supposition that the 

 indistinct grooves on each side of the middle line really represent the 

 lateral borders of the nasal bones, which is not certain, except as to 

 tlieir anterior portions. 



Measurements. mm. 



Widtii of skull at exoccipitals 406 



" " " postglenoid angles 570 



