no 



THE FUR SEALS OF THE PRIBILOF ISLA.NDS. 



Summary. — ^The ascaride of the Alaskan fur seal is specifically indentical with an 

 ascaride found in Phoca largha and Uumetopias stelleri in the same locality, and with 

 the form described by Krabbe in 1878 as Ascaris dedpiens from the stomach of Phoca 

 vituUna, P. groenlamdiea, P. Mspidu (=P.foeUda), P. barbata {=Urignathus bariatus), 



Trichechus rosmarus ( = Odobenus rosmarus), Gystophora 

 cristata and several undetermined marine mammals. 

 The species from Phoca barbata, described by Gobb in 

 1888 as Ascaris bulbosa, does not appear to differ essen- 

 tially from this form. Baird's (1853) Ascaris similis, 

 j ^ \ from the stomach of an Antarctic seal (see p. 147), and 



I "* ^ I ^^^ Ascaris bieolor, described in 1868 as parasitic in 



,\ f K?;4sv *^^ stomach of Trichechus rosmarus (see p. 142), are 



possibly also identical with Krabbe's species. The 



^8- 1- parasite has a wide geographical distribution, and is 



acquired by seals through eating fish. In detail the history of the worm is as follows: 



Historical review. — Eegarding A. similis, see page 147; for A. bieolor, see 



page 139. 



Krabbe (1878, pp. 45-47, r^sum^, pp. 11, 12) described this species from material 

 collected in Greenland by various persons (see p. 109) from Phoca groenlandica, P. bar- 

 bata {^Erignathus barbatus), P. hispida (^^P.foetida), 

 P. vituUna, Gystophora cristata, and Trichechus ros- 

 marus (== Odobenus rosmarus). Besides, these hosts, 

 from which the worms were collected, in all in seven- 

 teen cises, specimens were found 

 three times in unnamed seals from 

 Faroe (by Miiller), Iceland (by 

 Steincke), and Greenland (by An- 

 dersen). It was also found once in 

 -Phoca vitulina off the west coast of 

 Schleswig. The parasite often oc- 

 curs with A. osculata in the same 

 host, and for both of these species 

 the stomach is a more common hab- 

 itat than the intestine. In one case 

 a "couple of hundred" worms were 

 present, of which one- third were 

 males. The males attained 45'"'" in length, the females 60'"">. 



The lips are nearly alike, without intermediate lips; each lip 

 bears (fig. 1) a broad, rounded anterior double lobe, separated from 

 the basal portion of the lip by a lateral concave border. The inner 

 surface of the margin of the anterior lobe is provided with a den- 

 tigerous ridge, arranged iu a tripply curved line. Of the six pairs of 

 postanal papillae in the male (fig. 2) three pairs of conical papillae 

 are near the tip, and increase in size from the tip forward, so that 

 the third pair is the largest; nearer the anus are three pairs of 

 smaller papillae; anterolateral of the anus is situated on each side a row of conical 

 papillae, which increase in size from the first to the seventh or eighth. 



Fig. 2. 



Fig. 3. 



