ASCAKIS. 105 



which would be most favorable to the development of parasitic diseases, such condi- 

 tions in no way enter into the consideration of infection by the ascarides in question. 

 The infection takes place in the water, not upon the land. 



The maw worms collected in Bering Sea by Lucas have been referred to two 

 species, both of which have already been recorded for other parts of the world. 

 Ascaris decipiens was found in the material taken from the fur seal, the hair seal, and 

 the sea lion, and Ascaris osculata in the material taken from the sea lion. 



As these two species are considerably confused in helminthological works, not 

 only with each other, but with still other forms, it has been necessary to consult the 

 entire literature upon the ascarides of marine mammals; and as a knowledge of 

 the characters of all these parasites is. necessary in judging the forms found by Lucas, 

 it has been decided to incorporate in this report their descriptions, hosts, and 

 synonymy. 



THE ASCARIDES OF MARINE MAMMALS. 



According to Krabbe (1878), O. Fabricius (1780, p. 272— not accessible to us) 

 mentioned three species of nematodes, namely Ascaris phocae, A. bifida, and A. tubifera 

 from Greenland seals, but Krabbe states that none of these forms can be recognized. 

 Goeze (1782, pp. 73, 74) described an Ascaris phocarum collected by Soemmering in 

 1781 from Phoca vituUnaj the animals were 4J inches long and not quite a line thick. 

 Gmelin (1790, p. 3030) cites A. phocae, to which he refers Goeze's A. phocarum; he also 

 cited A. bifida; short diagnoses are given. Eudolphi (1793, p. 10) also refers to 

 A. phocae, but does not add anything to the description. 



The later history of these worms is intimately connected with the history of the 

 genera Bictularia Proelich, Ophiostoma Eudolphi, and Dacnitis Dujardin. As so much 

 uncertainty exists concerning the forms, and as they can not be properly judged with- 

 out a careful study of the history of the genera in question, they will not be considered 

 further in connection with this report. 



The history of the ascarides of marine mammals, so far as species recognized 

 to-day are concerned, begins with Eudolphi (1802), who described an Ascaris osculata 

 from Phoca. Between the appearance of Eudolphi's article containing a description 

 of this worm and the appearance in 1866 of Schneider's Monographic der Nematoden, 

 authors pretended to recognize Eudolphi's species and to distinguish from it certain 

 other species and genera described as new. 



With Schneider (1866) a new epoch in nematode literature began. This author 

 restudied Eudolphi's material, together with other specimens preserved in the Berlin 

 Museum, and gave good descriptions and figures. Very unfortunately he failed to 

 state in most cases whether the description of a given form was based directly upon 

 Eudolphi's originals or upon other material, so that in many cases we are left in uncer- 

 tainty regarding the weight which should be attached to his diagnoses of Eudolphi's 

 forms. As Schneider definitely states, however, that he examined Eudolphi's origi- 

 nals, and as his -work in reality represents the first extensive publication upon 

 nematodes prepared in a manner to be of much service, we consider it obligatory upon 

 us to accept his determinations ^.s correct until they are proved to be erroneous. We 

 consider g,ll literature upon the subject of the nematode parasites of marine mammals 

 published prior to 1866, and all determinations made before this date, except in so far 

 as the specimens have since been reexamined, as open to question. 



