348 BULLETIN OF THE BUREAU OF FISHERIES. 



In the paper already referred to Lefevre and Curtis call attention to the desirability 

 of reducing the length of the parasitic period of the glochidium (p. 191), which is inversely 

 proportional to the temperature of the water. Whether the shortening of the parasitic 

 period during the warm summer weather will compensate for the increase in the num- 

 ber of parasitic copepods is a question that can be decided only after careful experi- 

 mentation. We now know, however, that the presence of these copepods and their 

 periods of breeding are factors that must be given due consideration before the question 



can be solved. 



SYSTEMATIC. 



A complete description, fully illustrated with appropriate figures, is given of all the 

 species which are new to science. Of those which have been previously described only 

 such notes are included as are of interest or furnish additional information. The larvae 

 of a few species were hatched out in the laboratory of the station, and they also are 

 fully described and illustrated, since they add considerably to our previous knowledge 

 of the species. Several parasites were obtained by H. Kr0yer, a Danish zoologist, from 

 fish taken near New Orleans and sent to the Royal Museum in Copenhagen. Most of these 

 fish were such as come up the Mississippi River from the Gulf of Mexico, and hence their 

 parasites can not be included amongst the strictly fresh-water species; but they are 

 included in the present list because they are Hkely to be found in that part of the river. 



The parasites of fish in the Great Lakes, the Lake of the Woods in Canada, and of 

 several isolated lakes are also enumerated, since they are all fresh-water forms and really 

 belong with the great fresh-water fauna of the interior of our continent. A few species 

 have been included from west of the Rocky Mountains and east of the Appalachians. 



THE ARGUUD^. 



Argulus canadensis, new species. (PI. lx.) 



Host and record of specimens. — Three fine females were obtained by T. Surber at Le Claire, Minn., 

 from fish caught in the Lake of the Woods. Two were from a species of whitefish, Coregonus, while the 

 third was from a rock stm-geon, Acipenser rubicundus. The better of the first two is made the type of 

 the new species and has been given catalogue no. 43521, U. S. National Museum. The other has been 

 given catalogue no. 43525, U. S. National Museum, while the specimen from the sturgeon received 

 catalogue no. 43526, U. S. National Museum. 



Specific characters of the female. — Carapace elliptical, a little longer than wide, the posterior lobes 

 broad, evenly roimded, and reaching to about the center of the third thorax segment, leaving the two 

 posterior pairs of legs fully visible in dorsal view. Instead of projecting anteriorly the cephalic area is 

 slightly reentrant, ovate, and relatively very small; posterior sinus one-tliLrd the length of the carapace, 

 its width posteriorly equal to its length, but narrowed and squarely truncated anteriorly. The support- 

 ing rods in the lateral areas of the carapace are peculiarly arranged, meeting at a point far forward and 

 giving the creature a sort of hunch-backed appearance. The respiratory areas are also peculiar, the 

 outer one club-shaped, the large end anterior, while the handle of the club extends backward along the 

 outer margin of the inner area, an arrangement wholly different from anything heretofore described. 

 Abdomen a little more than one-fourth tlie entire lengUi, its wddth to its length as 5 to 8; anal sinus cut 

 beyond the center, its sides parallel, lobes narrow-elongate and rather bluntly rounded, papilla basal. 

 Eyes large and so far forward as to almost touch the anterior margin, but widely separated; sucking disks 

 also far forward and well separated, one-eighth the width of the carapace. 



Antennae small and weakly armed, the terminal joints of the first pair not reaching beyond the 

 lateral claw, tlie anterior claw minute and nearly straight; second antennas slender, basal joint enlarged 

 with a small spine on its posterior margin. A pair of large accessory spines behind the antennae and 

 close to the median line ; another pair between the bases of the maxillipeds or slightly posterior to them. 



