AiiT. 15 ANATOMY OF THE EAEED AND EARLESS SEALS HOWELL 109 



In the water this animal often swims partly on its side and when 

 coming to the surface for breath, will inhale through the corner of 

 the mouth as well as through the nose, as a human swimmer often 

 does. Perhaps more frequently, however, it will break water with the 

 tip of the nose and breathe through this member only, as the phocid 

 usuall}'^, if not always, does. It may be mentioned in this connection 

 that the epiglottis of Zalofhu^ appears to be unusually small for the 

 size of the animal, which one would not expect to be the case in an 

 aquatic form which habitually comes to the surface for quick breaths. 

 I have encountered no statements regarding the possible duration 

 of submergence of the Pinnipedia which I regard as both significant 

 and trustworthy. In captivity an animal seldom experiences any 

 incentive for lengthy submergence and I have never seen one do so 

 for more than about two minutes. If frightened in the wild, the 

 animal which reappears can not always with confidence be regarded 

 as the same one which has disajDpeared. It seems certain that all pin- 

 nipeds must be able to stay beneath the surface for some considerable 

 time, while it would seem absolutely essential that the boreal mem- 

 bers of the Phocidae, at least, which must often have to swim be- 

 neath extensive ice floes, should have this faculty especially devel- 

 oped. Of undoubted importance in the present connection is the 

 development in this order of a large hepatic sinus, consisting of a 

 lemarkable dilation of the vena cava dorsad of the liver. For the 

 Phocidae this was said by Murie (1874, p. 545) to have been reported 

 and illustrated by Barkow (presumably H. C. L. Barkow in the 

 early nineteenth century), but I have been unable to find the article 

 to which he refers. Murie (1874) states that in his Euvietopias the 

 sinus occupied " a volume, one might almost say, greater than the 

 glandular hepatic organ itself." In examining the viscera of the 

 Phoca hispida which I dissected, Paul B. Johnson encountered such 

 a sinus, dilatable to contain perhaps 2 quarts, but in the younger 

 Zalophus it was much less developed. It is, therefore, possible that 

 this sinus is developed with age and that it is largely lacking in 

 juveniles. It is, of course, apparent that it serves as a reservoir to 

 hold an extra amount of blood and hence to prolong submergence by 

 just so much. Throughout sealing literature one often encounters 

 statements to the effect that pinnipeds appear to be veritable sacks 

 of blood. 



While on the subject of the viscera it may be well to mention, in 

 passing, the habit of the Pinnipedia of swallowing stones, sometimes 

 as large as an Q,gg and aggregating as much as 3 pounds in weight. 

 The reason for this action has not been determined. 



In the Zalophus the ear is slender and had a length of 28 nrni. 

 The external opening of the auditory tube is small and the pinna of 



