COPEPOD PARASITES AND MUSSEIv GLOCHIDIA ON FRESH- WATER FISHES. 349 



The supporting rods of the membranous border of the sucking disks are made up of an oblong basal 

 joint and a series of lo or ii plate-like disks, overlapping one another like shingles and diminishing in 

 size distally, similar to those in Argulus mcgalops. The basal joint of the maxillipeds is much swollen, 

 the basal plate does not quite reach the posterior margin, and is armed with three slender acuminate 

 teeth; this plate has a rounded lobe outside of the teeth, which carries a short spine at its center. The 

 ventral protuberance is large in area, oval in outline, and is put on diagonally, the small end filling 

 out the rounded external lobe just mentioned; there are also spiny areas at the distal end of the basal 

 and third joints, and over the whole siuface of the second joint; there are two terminal claws and a 

 fingerlike process outside of them. 



Color (preserved material), carapace, abdomen, and the entire ventral svuface a clear creamy white; 

 dorsal surface of the thorax covered with rounded spots of a deep reddish purple, with a white streak 

 through the center above the intestine; tliese spots extend forward beneath the carapace as far as the 

 mouth; eyes and semen receptacles a lighter purple. 



Total length, 12 mm.; carapace, 7.2 mm. long, 7 mm. wide; abdomen, 3.4 mm. long, 2.2 mm. wide. 



{canadensis, Canadian.) 



Remarks. — This is a large and powerful parasite and is evidently oiu" American representative of 

 the European species coregoni. It would be interesting to ascertain whether they produce any such 

 effect on the fish in tlie Lake of the Woods as is recorded for the fish of the lakes in Jemtland by Dr. 

 Nystrom. (Proceedings U. S. National Museum, vol. 25, p. 725.) 



That our species is distinct from coregoni is shown by the following differences. There are no 

 flagella on any of the legs, while in coregoni they are full sized. The cephalic area is reentrant anteriorly 

 instead of protuberant. The eyes almost touch the anterior margin and are ratlier small. There is no 

 ovate papilla on either side of the opening of the oviduct, which Thorell makes one of the prominent 

 characters of coregoni. The respiratory areas are very different, not only from coregoni but from every 

 other known species of Argulus. This is evidently a northern species, since it has not been found upon 

 any of the numerous species of Coregonus in the Great Lakes. The male is as yet unknown. 



Argulus flavescens, new species. (PI. lxi, fig. 7-12.) 



Host and record of specimens. — ^Two females were obtained from the outside of the dogfish, Amia 

 calva, caught in "Sunfish Lake," near Fairport, Iowa, August 8, 1914. The better of the two is made the 

 type of the new species and has received catalogue no. 47759, U. S. National Museum; the other becomes 

 a cotype with catalogue no. 47760, U. S. National Museum. A third mutilated specimen was obtained 

 from the gills of the mud cat, Leptops olivaris. 



Specific characters of female. — Carapace elliptical, a little longer than wide, and evenly rounded; 

 lateral sinuses scarcely perceptible ; posterior sinus more than twice as long as wide , and two-fifths the 

 length of the carapace, with nearly parallel sides; posterior lobes not reaching the abdomen, broad and 

 plump ; abdomen broadly ovate , as wide as long , and narrowed to a short neck where it joins the thorax ; 

 anal sinus about one-third the length of the abdomen, considerably enlarged at the base; anal papillae 

 spherical and basal. 



Entire under surface of the body, including the abdomen, covered with small spines, pointing 

 backwards; eyes small, placed well forward and some distance apart, facets minute; lateral ramifications 

 of the stomach large and particularly prominent by reason of their color and lobed edges; respiratory 

 areas made up of a small anterior, nearly circular portion, and a long posterior portion, which reaches 

 nearly to the tip of the posterior lobes; sucking disks of medium size, placed well forward and close 

 together. First antennae slender, the anterior claw rudimentary, the lateral claw curved into three- 

 quarters of a circle, the two terminal joints slender and reaching well beyond the tip of the claw. Second 

 antennae with swollen basal joint and three long terminal joints, abruptly reduced to one-third the 

 width of the basal joint and sparsely armed with setse; a small flattened spine on the basal joint of each 

 antenna and an accessory pair of larger and sharper spines posterior to the second antenna and close to 

 the midline. 



Basal plate of the maxillipeds small and narrow, with short, flattened, and bluntly rounded teeth; 



raised area a long and narrow oval ; the four terminal joints each with a roughened area along the anterior 



and distal margins; last joint tipped with two minute claws and a fingerlike process. Swimming legs of 



the usual pattern , the posterior pair with a small lobe, which is not boot-shaped, but flares at both ends, 



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