INTRODUCTION. 101 



anything ever been found other than the bile and ordinary secretions of healthy organs of this class, 

 ■with the marked exception of finding in every one a snarl or cluster of worms (Nematoda) from the 

 size of a walnut to a bunch as large as a man's fist. Fasting apparently has no effect upon the worms, 

 for on the rare occasion, and perhaps the last one that will ever occur, of killing three or four hundred 

 old bulls late in the fall to supply the natives with canoe skins, I was present, and again examined 

 their paunches, finding the same ascaridae ■within. They were lively in these empty stomachs, and 

 their presence, I think, gives some reason for the habit which the old bulls have (the others do not) of 

 swallowing small water-worn bowlders, the stones in some of the stomachs weighing half a pound 

 apiece; in others, much smaller. In one paunch I found over 5 pounds, in the aggregate, of large 

 pebbles, which, in grinding against one another, I believe, must comfort the seal by aiding to destroy 

 in a great measure those intestinal posts. 



The sea lion is also troubled in the same ■way by a similar species of worms, and I preserved the 

 stomach of one of these animals in which there was more than 10 pounds of stones, some of them alone 

 very great in size. Of this latter animal, I suppose it could swallow bowlders that weigh 2 or 3 pounds 

 each. I can ascribe no other cause for this habit among those animals than that given, as they are 

 the highest type of the carnivora, eating fish as a regular means of subsistence, varying the monotony 

 of this diet with occasional juicy fronds of seaweed or kelp, and perhaps a crab or such once in awhile, 

 provided it is small and tender or soft-shelled. I know that the sailors say that the Callorhinus 

 swallows stones to "ballast" himself; in other words, to enable him to dive deeply and quickly; but 

 I noticed that the females and the "holluschickie" dive quicker and swim better than the old fellows 

 above specified, and they do so without any ballast. They also have less muscular power, only a tithe 

 of that which the "see-catch" possesses. No, the ballast theory is not tenable. 



In the Report of the British Oommissioners (p. 97, sec. 343) in the Paris Arbitra- 

 tion the following rather indefinite reference to the parasites of seals is found : 



The fur seals upon the Pribilof Islands are, however, afflicted by at least one known trouble, 

 that of intestinal worms, and in the stomachs of every seal killed a certain nuinber, and often a very 

 considerable number, of such worms are found. This can not, of course, be considered as constituting 

 in itself a very serious affection, but if under any particular train of circumstances it should be 

 considerably increased, it alone might become a danger to the continued well-being of the seals. 



These, so far as we are aware, are the only published statements regarding the 

 parasitic worms found in Bering Sea. The preliminary study of the parasitic diseases 

 of the fur seal is thus reduced to indefinite and vague statements of little or no value. 

 We may, however, expect that a review of the parasites of marine mammals will aid 

 us in the subject at hand, as basis for comparison and inference, and it will be well, 

 therefore, to take a glance at the literature upon this subject before passing to a 

 determination of the worms collected by Lucas in Bering Sea. 



The greater part of the literature upon the parasites of marine mammals is purely 

 zoological, dealing with descriptions, lists, and synonymy of forms found in various 

 parts of the world. 



Both worms and arthropods have been found parasitic in or upon marine mam- 

 mals. So far as the effect of animal parasites upon these hosts is concerned, the 

 majority of helminthological articles do not refer to it. The following references to 

 this subject have, however, been found: 



Murie (1868) gives an account of a post-mortem examination upon a young male 

 walrus which died at London. In this account, which is reprinted in full in connect 

 tion with the parasite present (see p. 139), Murie found a large number of worms, 

 Ascaris bicolor Baird, in the stomach, to the presence of which he attributed a con- 

 gestion and ulceration of that organ. He also states that an abscess was found in tbe 

 brain. In one portion of the account Murie says that "death seems to have resulted 

 from the ulceration of the stomach," although he admits that "it is not clear why the 

 animal should have succumbed so suddenly," and adds: "Literally speaking, these 



