46 PEOCEEDIN-GS OF THE NATIOISrAL MUSEUM vol. 73 



oephalus, but the muscle was not mentioned by Murie for Eumetopias 

 or Odoberms. 



M. pterygoideus internus (figs, 3, 4) in the Zalophus was much larger 

 than the externus, arising from the border of the bony wall of the 

 interpterygoid fossa and practically coinciding with the extent of 

 the palatal bone along this border. Insertion was below the condyle 

 of the mandible. In the Phoca origin was similar save that it 

 extended as far rostrad as the maxillary root of the zygoma. Inser- 

 tion was along a ridge upon the medial side of the caudal border of 

 the mandibular ramus that extended from the angular process to 

 within a short distance of the condyle. Substantially the same for 

 P. mtvXino) and Arctocephalus but not mentioned by Murie for Ewne- 

 topias and Odohenus. 



3. INTERRAMAL MUSCULATURE 



M. digastricus (figs. 4, 5, 6, 18, 19) was monogastric in both. In the 

 ZalopJiAis origin was from the whole lateral border of the paroccipital 

 process, with insertion upon the caudal three-fifths of the ventro- 

 medial border of the mandible, extending also just laterad upon a 

 slight prominence ventrad of the masseteric fossa. In the Phoca no 

 tendinous division was noted, such as mentioned by Miller for P. 

 vitidina, but origin was evidently the same, being from the depression 

 upon the mastoid directly caudad of the center of the bulla. The 

 muscle then spread so as to invest the entire audital bulla. The 

 insertional end was much smaller than in the Zalophus, the attach- 

 ment being to the medial side of the inferior border of the mandible, 

 from the angular process craniad for several centimeters. Murie 

 found a slightly tendinous division of the muscle in Odohemis, but 

 not in Ewnetopias. 



M. stylohyoideus (figs. 18, 19) in the Zalophus was represented by 

 but a few fibers deep to the digastric, extending from the region of 

 the stylohyal, though not definitely from any part of the temporal 

 bone, with insertion onto the basihyal. In the Phoca there was a 

 very thin slip from below the auditory meatus to the basihyal, but 

 superficial to the digastric, as in man. Miller gives this normal 

 origin and insertion for this muscle in his phocids but fails to state 

 its relation to the digastric. In my Phoca there was another slip 

 upon the left side deep to the digastric, as in the Zalophus, but it 

 seemed to pass entirely dorsad of the basihyal and disappeared in the 

 neighboring tissue. It was noted as questionable in homology and 

 when an attempt was made to verify it upon the right side it could 

 not be found. Murie did not discuss the muscles of this region in 

 his Otariidae. 



