12 PKOCEEDINGS OF THE NATIONAL MUSEUM vol.73 



such a degree that these have actually forced their way here and there 

 through the fragile frontals which overlie them. An occasional 

 Zalophus skull has what appears to be an imperforate lachrymal be- 

 tween the maxilla and frontal just within the orbit. In the search 

 for this bone in the Phocidae one needs be careful to identify the 

 maxilloturbinal, a smooth part of which is often to be seen on 

 the border of the orbital vacuity. Certainly the bone is entirely 

 absent in the vast majority of phocids. having either dwindled and 

 disappeared from the maxillo-frontal suture, or what seems more 

 logical, has been forced by the enlargement of the orbit relatively 

 farther caudad, and now represented perhaps by cartilage within the 

 confines of the maxillo-frontal vacuity, which cartilage would dis- 

 appear during cleaning of the skull. In Stenorhynchus only among 

 phocids have I been able to find a bone which might represent the 

 lachrymal and the homology of this is uncertain. In a single skull 

 of this genus there is a small bone bounded by the vacuity, maxilla 

 and palatal which may be the lachrymal. The maxillo-frontal 

 vacuities of the orbit are usually much larger in the otariids than 

 phocids, although the smallest in the former may be no larger than 

 the greatest in the latter. The infraorbital foramen is relatively 

 larger in the Zalophus than in P. hispida^ but there is much varia- 

 tion in this item within the two families. Its size in the pinnipeds 

 is an index to the development of the infraorbital nerve, which 

 serves the mystacial pad. The maxillo-naso-labialis muscle, which 

 is the chief mechanism for opening the anterior nares, arises from 

 the maxilla directly caudo-ventrad of the infraorbital foramen. The 

 point of origin is not indicated upon the skull of Zalophus nor of 

 most phocids, but it is marked by a relatively deep fossa in P. 

 hispyidu: The only noteworthy feature of the zygoma that has not 

 been mentioned is the apparent fact that in the Otariidae the malar 

 extends to the glenoid fossa, which it does not quite do in the 

 Phocidae. One not infrequently encounters the statement that in 

 the Otariidae the dorsal process of the zygomatic arch occurs 

 definitely craniacl of the jugal-squamosal suture, while in the 

 Phocidae it occurs either at this point or a bit caudad. This is a 

 secondary character and the position of the process is attributable 

 to the relative size of the orbit, and hence, of the eye. As usual the 

 zygoma tells little in regard to the masseter muscles. 



The molars of the Otariidae are simple and conical, evidently hav- 

 ing assumed their present form because of the slight use to which they 

 are put in simply helping to tear fish and similar food, rather than 

 in shearing tough meat and gnawing bone, as is the habit of the 

 fissiped. The molars of the Phocidae are of a more complicated 

 form and have at least two cusps — often more. Presumably the food 

 predilections of all pinnipeds are very much the same, and it is not 



