448 Berry and Gregory — Prorosmarus alleni. 



inclined backward and is l*9 cm in diameter and 3"8 cm in depth. 

 The fourth alveolus indicates a considerable backward inclina- 

 tion of the contained tooth, and is l - 8 CDa in diameter and 3*2 cm in 

 depth. Thus we see a progressive shortening- of the alveoli 

 from before backward, but apparently no diminution worth 

 taking into account in the diameter of the teeth for the whole 

 molariform series. There is no indication of an additional 

 molar, which is remarkable, when we consider the large size of 

 the fourth premolar, and indicates that the fifth tooth in the 

 molar series was vestigial or absent. 



Anterior mental foramen large. Mandibular symphysis 

 ll cm long and 4 cm in greatest height, very massively corrugated 

 throughout. The muscular attachments are all strongly marked. 



♦ Measurements. 



Total length, condyle to incisive border (estimated) . . 21'5 cm 



Anterior border of first " molar " (pj to posterior border of 



coronoid (estimated) 17 



Breadth of coronoid at base 2 - l 



Horizontal diameter of coronoid at base ... 4*5 



Length of molar series _- 8 



Antero-posterior diameter of alveolus, first incisor __ 8 mm 



" second " 13 



" canine 17 



" pm i .- 17 



" p 2 18 



P,— > 19 



P. ; 18 



Estimated depth from top of coronoid to angle of jaw 10 cm 



Depth of jaw behind p 4 6*1 



" " below p 3 - - 6 



" " " p 2 --- -..6-9 



" " " p, ■ 7-5 



" " " canine . 5 



Height of canine crown 21 mra 



Extreme length of symphysis 1 l cm 



Thickness of ramus 3 - 5 



Breadth of jaw opposite canine (estimated) .. _ 7 



The species is named in honor of Dr. J. A. Allen of the 

 American Museum of Xatural History, author of well known 

 contributions on the Pinnipedia and other marine Mammalia. 



Relationships of Prorosmarus. 



Prorosmarus seems to have been only one of a number of 

 genera of Odobsenidae which must have flourished during the late 

 Miocene and Pliocene epochs. Of these, the European forms 



