COPEPOD PARASITES AND MUSSEI< GLOCHIDIA ON FRESH-WATER FISHES. 353 



These tiny specimens were very active and moved about much more constantly and with more 

 speed than the free-swimming forms. They were so thin as to be almost perfectly transparent and made 

 excellent microscope mounts. Their abnormal abundance was doubtless due to the congested con- 

 ditions in the places where they were found, as already noted (p. 335). 



Argulus stizostethii Kellicott. (PI. lxii, fig. 20.) 



ArgtUus stizostethii, Kellicott, Amer. Jour. Micros., vol. 5, p. 53: Wilson, Proc. U. S. Nat. Mus., vol. 25, p. 713, pi. 17. 



Host and record of specimens. — This species was originally obtained by Kellicott from the wall-eye, 

 Stizostedion vitreum, in the Niagara River near Buffalo. Adult specimens have been obtained by the 

 author from wall-eyes and saugers, 5. canadense, in the Mississippi River and from wall-eyes in Lake 

 Maxinkuclcee. Young specimens of both sexes less than 1.50 mm. in length were taken in considerable 

 numbers in the tow at "Sunfish Lake," near Fairport, August 2, 1914. These were associated with 

 A . Upidostei, the numbers of the two species being about even, but the males of both species much more 

 numerous than the females. 



Specific characters ojjemale. — These small Arguli being transparent, it was possible to make out the 

 nervous system with ease. Comparing it with that of other species, we may notice first the exception- 

 ally large size of the eyes, each of which is as large as the entire supraesophageal ganglion. The optic 

 nerves are also very large and swollen into a barrel shape. 



The first of the ventral chain of ganglia is enlarged laterally to nearly twice the diameter of the 

 four following ones, which are all the same width, but the second and fifth ones are three times the 

 length of the third and fourth. The nerves are given off exactly like those in A . americanus (Proceedings 

 U. S. National Museum, vol. 25, p. 633). 



The supporting rods in the membranous border of the sucking disks are made up of 10 or 12 parts; 

 the basal one is a narrow oblong with concave sides, the second, third, fourth, and fifth are much wider 

 but about the same length, conve.K posteriorly and concave anteriorly; the remaining parts are more or 

 less completely fused into a narrow threadlike rod. 



The bordering fringe is narrow and made up of short and stiff hairs. The male was fully described 

 in the references above given, and there is nothing to add here. 



Remarks. — This species is not as common as the preceding; it was originally obtained from the 

 wall-eye, but Kellicott records that specimens placed in an aquarium with the long-nosed gar and 

 some minnows fastened on them and eventually killed the minnows. This suggests that under natural 

 conditions they may often fasten on other fish than their usual host, especially imder the conditions 

 prevailing in the slews and "lakes." 



Its presence in such numbers in the tow is indicative that the species must be fairly common in the 

 vicinity. 



Argulus appendiculosus Wilson. 



ArfftUus appendiculosus Wilson, Proc. U. S. Nat. Mus., vol. 32, p. 419, pi. 32. 



Host and record of specimens. — The types of this species were obtained from a sucker (species not 

 given) at Montpelier, Vt., and were sent to the United States Bureau of Fisheries at Woods Hole, Mass., 

 in August, i8g8. 



Since the original description it has been found in several places in the Mississippi Valley, as follows: 

 A single female from the outside of the channel cat, Ictahirus punclatus, at Cumberland Falls, Ky., 

 July 7, 1911, catalogue no. 39588, U. S. National Museum; a male and female from the outside of the 

 sheepshead, A. grunniens, at Lock 21 on the Cumberland River in Kentucky, catalogue no. 43523, 

 U. S. National Musetun; several specimens of both sexes from the largeraouth black bass, M. sal- 

 moides, at Fairport, Iowa, July 20, 1912, catalogue no. 43527, U. S. National Museum; two males and 

 two females from the outside of the redmouth buffalo, Ictiobus cyprinella, at Fairport, May 27, 1910, 

 catalogue no. 43542, U. S. National Museum; a male and female from the smallmouth buffalo, /. bubalus, 

 at Fairport, June 28, 1914, catalogue no. 47761, U. S. National Museum. Isolated specimens were also 

 obtained from the gizzard shad, Dorosoma cepedianum, the crappie, Pomoxis annularis, and the white 

 bass, Roccus chrysops, which goes to prove that these fish at least serve as occasional hosts. 



Remarks. — This species was established in 1907 upon 20 specimens taken from a sucker at Mont- 

 pelier, Vt., and both sexes were fully described and figured in the reference above given. All that can 

 be added here is a few data with reference to the color. Both sexes when alive are a transparent creamy 

 white, covered on the dorsal surface of the carapace and abdomen with opaque white dots, circular in 



