CONTENTS OF A BONE CAVE. 23 



palatine bone extends forwards on the middle line to opposite the middle of the 

 dental series. In front of the processus pyramidalis, and separated from it by a 

 deep fissure, the thin lamina perpcndicularis rises. Its anteroposterior diameter 

 is greater above than below. Its anterior margin articulates by squamosal suture 

 with the interior side of the superior alveolar wall of the maxillary bone. This 

 wall is so strongly convex as to divide the maxillary sinus into two fossae, an inter- 

 nal large, and external small. The latter is bounded internally by the wall of the 

 infraorbital canal, which extends along the summit of the alveolar arch. The 

 nasal roof of the antrum is thin, and only extends as far posteriorly as the middle 

 of the first true molar. The posterior extremity of the malar bone is deeply 

 notched, and was connected with the frontal, inclosing the orbit behind. 



The palate is rather wide, and the molar series is curved or convex outwards. 

 The posterior external column of the last true molar is half as wide again, in antero- 

 posterior diameter, as the corresponding anterior column. The vertical ribs are 

 most prominent in the second and third true molars, the anterior being obsolete 

 on the first true molar, and wanting on the premolar. In all the molars the anterior 

 column has a median external rib, which is strong on the first true molar, less 

 marked on the other teeth, and wanting on the posterior column in all. The two 

 inner columns are separated by a vertical fissure to a considerable depth in the 

 second true molar, but not in the first. There is a slight contraction of the anterior 

 lake of the first true molar caused by a low rib on the posterior part of its internal 

 enamel wall. 



The form of the face is short and high, the facial plate of the maxillary rising 

 above the level of the lachrymomalar suture. The external foramen of the infra- 

 orbital canal is large, and issues above the posterior part of the premolar. There 

 is no lateral facial fossa. The inferior orbital border is strongly flared outwards. 

 The posterior palatal notch enters as far as the anterior margin of the last molar, 

 and the external pterygo-maxillary notch is not quite so deep. The palato-maxil- 

 lary suture leaves the alveolar border at the front base of the last molar. 



MEASUREMENTS. 



M. 

 Length of entire molar scries . . .... .047 



" of true molars ....... .039 



Diameter of preraolar j ">teroposterior . . .0075 



(transverse ..... .0055 



" of first molar Anteroposterior . . .0120 



(.transverse ..... .0055 



of second molar | anter P sterior ' 13 



(.transverse .... .006 



Width of palate in front of premolar . . .014 



" at second true molar .... .030 



Associated with the cranial mass already mentioned as representing this species, 

 there are several bones of the skeleton of an immature mammal, which are appro- 

 priate to it in size and proportions. These are an axis and a dorsal vertebra, 

 humeri, radius, pubis and ischium, femur and cannon bones, all without epiphyses. 



I now describe the other bones already mentioned. There is no sinus in the 



