1885.] DR. ST. G. MIVART ON THE PINNIPEDIA. 497 



never overlapped by a ridge of bone running from the par- 

 occipital process to the condyle, and never opens into, though 

 it appears sometimes to coalesce with, the foramen lacerum 

 posterius. 



(7) The glenoid foramen is always very small, and is sometimes 



not to be detected. 



(8) The alisphenoid canal may be present or absent, as already 



mentioned more than once. 



(9) The suborbital foramen is always rather large ; but never as 



large relatively as in Lutra and Enhydra. It is largest in 

 Trichechus. 



(10) The frontal postorbital process present in Otaria and Triche- 



chus is never more than a rudiment in the PhocidcB. 



(11) The zygomatic postorbital process is farmed both by the 



malar and squamosal in tlie Fhocidce, mainly by the malar 

 in Otaria, and entirely by it in Trichechus. 



(12) The alisfiheuoid and parietal always join by a narrow process 



of the latter bone. 



(13) The premaxillue never ascend to join the frontals. 



(14) There is never a lachrymal foramen. 



(15) The basis cranii is nearly always bent, so as to be convex 



downwards. 



(16) The anterior nares are quite terminal in Trichechus, rather 



more distant from the end of the muzzle in Otaria, and not 

 at all terminal, but looking more or less exteriorly upwards 

 as well as forwards, in the Phocidce. 



(17) The opening represents both the foramen rotundum and the 



spheno-orbital fissure. 



(18) The optic foramina open into the cranial cavity by a single 



aperture in Otaria and in Stenurhynchus, but not in the 

 Phocidce generally, as in Trichechus. 



(19) The palate always extends backwards much behind the last 



molars, but is not commonly narrowed behind save in Otaria. 

 It is not at all so narrowed in 'Trichechus. 



(20) Defects ot ossification commonly occur in the occipital in the 



Phocidce, but not in Otaria and Trichechus. 



(21) A preorbital process exists in Otaria and Trichechus ; some- 



times, but rarely, in the Phocidce. 



(22) The angle of the mandible is inflected (as in Marsupials) in 



Otaria, but not in the other genera. 



It is now generally agreed to regard the Pinnipeds as derived 

 from Ursine Arctoids ; and there can be little doubt as to this origin 

 as regards Otaria. But it is not absolutely necessary that the whole 

 Order of Pinnipeds should have had but a single origin. It is at 

 least conceivable that the Otaries might have been derived from 

 Bear-like animals, while the Phocidce had another, possibly a Lutrine, 

 origin. If this hypothesis were correct, the Pinnipeds would of 

 course consist of two strains which have gradually grown to be more 

 and more alike. I have no intention of maintaining the probable 



