370 



BULLETIN OF THE BUREAU OF FISHERIES. 



Lemseocera pectoralis Kellicott. 



LenuBOcera pectoralis Kellicott, 1882, Proc. Amer. Soc. Microscopists, vol. 4, p. 77. 



Host and record of specimens. — A dozen females were obtained from the red-finned shiner, Notropis 

 cornutus, in the Shiawassee River at Corunna, Mich., in July and August, 1881. They were fastened 

 to reddish lumps in the axils of the pectoral fins. None of these original specimens have been preserved 

 and no others have been obtained, so that Kellicott's description gives us all the knowledge we possess 

 of the species; he published no figures. 



Specific characters of female. — Body strongly bent and club-shaped; three horns on the cephalo- 

 thorax, the two lateral ones three or four pronged, the dorsal one stout and forked at the apex. Body 

 indistinctly segmented; the lateral tubercles at the posterior end small, the median dorsal tubercle, 

 the abdomen, much longer and wider, and extending far over the bases of the ovisacs; the latter are 

 short and club-shaped. 



Total length, 7.50 mm.; width of horns, 1.70 mm. 



Remarks. — This species resembles L. tortua but is little more than half as long, the dorsal horn is 

 forked, the egg strings are shorter and club-shaped, and the terminal setae on the anal papillae are not 

 plumose. 



None of these species of LenuBocera are as yet well enough known to enable us to 

 estabhsh their relations with the mussel glochidia. Whatever may be the relations of 

 the adult fastened in the flesh of its host to the mussel glochidia on the fins, it is reason- 

 ably certain that the copepodid larvae of the various species of LerncBocera are much more 

 closely related to the glochidia on the gills. Before we can understand this relation 

 thoroughly, there must be considerable more research and observation on the genus. 



To facilitate the distinctions between the different species, the following table may 

 be presented ; in it the entire length of the parasite is taken as loo units, and the distance 

 of the four pairs of swimming legs from the anterior border of the head (excluding the 

 horns) is given in percentages of loo. 



It is almost certain that the absolute distances vary in the same species with the 

 development of the individual ; the older the parasite becomes the farther removed are 

 the legs from the head; but the relative distance of the pairs one from another ought 

 not to vary much, and it is these relative distances that are expressed in the above table. 



The male does not develop beyond the fourth copepodid stage and never attaches 

 itself to the flesh of a fish nor to the body of the female, but after the mating of the 

 sexes the male dies. This makes it necessary to secure the male from the tow or from 

 the gills of some fish prior to the mating, by no means an easy task; but these males 

 and the copepodid stages of the females furnish the data which will eventually decide the 

 validity of the various species, as well as their economic relations. 



GENERAL REMARKS. 



In a recent paper by Dr. W. A. Cunnington, which is a report on the parasitic 

 Eucopepoda and forms part of the "Zoological Results of the Third Tanganyika Expe- 

 dition,"" he says : " It is clear that whatever may be the case for marine fishes, the fishes 



a Proceedings Zool. Soc. London, 1914, p. 819-829, pi. i. 



