108 U. S. BUREAU OF FISHERIES. 
the erroneous term “ rubbed spots.” These are usually on portions of 
the anatomy which could not be “ rubbed” under any circumstances. 
The number of cases of this disease gradually decreased to a mini- 
mum by 1917, which remained constant through 1920. 
Ectoparasites of the fur seal are very rare, although the enormous 
amount of scratching which is visible in any “ pod” would leave the 
casual observer with the impression that the opposite is the truth. 
In 1899 a louse, Zematopinus callorhini Osborn, was described from- 
“a number of examples from the northern fur seal.” And at the 
same time a tick, /aodes arcticus Osborn, was described from a single 
individual.t. I have made repeated search for these parasites, and 
several years ago located the louse on pups. Not all are afflicted by 
any means, but occasionally a few specimens can be secured from the 
eyelids and less often in the fur of the head. No positive information 
regarding the tick could be secured. A reward of $1 per louse 
and $5 per tick has been offered to the native workmen who kill 
and skin some 25,000 animals each year, but there have been only 
negative results. This leads me to believe that the louse is almost, if 
not wholly, confined to the pups, and very serious doubt is cast upon 
the /xodes arcticus being a parasite of the fur seal at all. 
COWS. 
The number of breeding cows in the herd corresponds to the num- 
ber of pups, since the one is derived directly from the other. There 
naturally exists in any year an excess of adult females over young, 
because there are always a few barren animals. The number, how- 
ever, has never been considered other than inconsequential and is 
very properly ignored. The increase or decrease, in fact the exist- 
ence of the species, is dependent upon the fertile cow; the others in 
no known way enter into commercial operations of man. 
Formerly it was supposed that the cows which resorted to the 
hauling grounds with the bachelors were barren, but this is not the 
case at all. Thirteen cows which had been accidentally killed on the 
fields during the past four years have been examined and only one 
was found barren. Several of them had already given birth to 
young, but others had not, while the majority were 2-year-olds with 
reproductive organs normal in every way. 
LOSS OF COWS ON THE ISLANDS. 
The spreading of the bulls incident to the larger average harem 
produced a noticeable decrease in the death rate of cows on the 
breeding grounds. Since much of the turmoil and fighting of the 
past three years was thus done away with, such a result would be 
naturally expected. During the counting of 15,965 pups 9 dead 
cows were found. This is a percentage of 0.000563, which applied to 
the entire herd gives 94 as the total number. Comparable figures for 
preceding years were: 195 in 1919, 213 in 1918, 129 in 1917, and 39 
in 1916. It shows that in spite of the increase in the herd there 
1Fur Seal Investigations, 1896-97, pt. 3, p. 553. 
