COPEPOD PARASITES AND MUSSEL GLOCHIDIA ON FRESH -WATER FISHES. 351 



with short spines, on the ventral surface of the basal joint of the second legs, at each end of which is a 

 stiff lingerlike projection; the basal joint of the third legs carries a boot-shaped posterior lobe fringed 

 with setas; on the anterior margin, parallel with the axis of the joint, is a fingerlike process, covered with 

 short spines, whose tip is turned forward just beyond the distal end of the joint; inside of this tip is 

 the base of another long process, flattened anteroposteriorly and covered with short spines, which extends 

 outward parallel with the second joint and overlaps the bases of the rami; on the posterior margin of 

 this second joint, distal to the opening of the semen receptacle, is a small laminate process, fringed with 

 long setae; the musculature of these two basal joints is peculiar, as may be seen in fig. 27. The peg on 

 the fourth leg is double and stouter than in most species. 



Total length of figured specimen, 11 mm.; carapace, 7.50 mm. long, 9 mm. wide; abdomen, 3.50 

 mm. long, 2.50 mm. wide. 



Color of both sexes: Carapace, abdomen, and the ventral surface a light yellow, thickly sprinkled 

 on the dorsal surface with small circular dots of light cinnamon brown. There are no spots on the thorax 

 but the dorsal surface of the oviducts beneath the muscles is dark cinnamon brown, and it shows through 

 very plainly; semen receptacles and testes dark orange yellow; eyes deep cinnamon bro^vn. 



(mississippiensis, of or belonging to the Mississippi River.) 



Remarks. — With the exception of A rgulus ingens, this is the largest species of the genus in America, 

 and the measurements sometimes exceed those given above. For example, one female was found which 

 measured 20 mm. in length, while one of the males was 15 mm. long. In addition to its large size it 

 presents many peculiarities of structure, the most noticeable being the double lobes on the fourth legs, 

 the peculiar papilla on the sides of the anal sinus, and the complicated respiratory areas. One of these 

 parasites is as large as an ordinary copper penny and must drain the blood of its host quite severely. 

 Fortunately for the fish, it is rare to find more than one parasite on a single fish; otherwise they would 

 soon drain its blood. The present species completes the list and is the third found upon the gars, so 

 that each gar now has its peculiar parasite, A rgulus lepidostei upon the long-nosed gar, A . mississippiensis 

 upon the short-nosed gar, and .4 . ingens upon the alligator gar. 



Argulus lepidostei Kellicott. (PI. Lxn, fig. 16-19; P'- LXiv; pi. lxv.) 



Argulus, lepidostei, Kellicott, Bull. Buffalo Soc. Nat. Sci.. vol. 3, p. 214, 1877: Wilson. Proc. U. S. Nat. Mus., vol. 25, 

 p. 712, pi. 16. 



Host and record of specimens. — Twenty males and twenty-one females were obtained from the short- 

 nosed gar, Lepisosteus plalostomus, at Fairport, June 23, 1914, by Dr. A. D. Howard; they have been 

 given catalogue no. 43543, U. S. National Museum. One male and a female were taken from the long- 

 nosed gar, L. osseus, at Defiance, Ohio, by H. W. Clark; these have received catalogue no. 43522, U. S. 

 National Museum. Most of these were found near the pectoral fins of their host, as was recorded of the 

 original specimens by Prof. Kellicott. 



Specific characters of female. — In addition to the descriptions given in the above references we may 

 note the following: The respiratory areas are situated close to the posterior end of the lateral lobes; the 

 outer and larger area is ciu-ved parallel with the margin of the carapace, its anterior end is narrowed, 

 while the posterior end is thickened; the smaller and inner area is elliptical in outline and is inserted 

 in the inner margin of the outer area near its anterior end (see fig. 29). 



The ventral surface of the carapace is covered with orange-colored spines pointing backward. The 

 color of the living female is a pale lemon yellow in young specimens, with only a few spots of cinnamon 

 brown. These spots increase in size and number with advancing age and in full-grown adults become 

 continuous along the dorsal surface of the free thorax. The eyes are deep violet brown, the semen 

 receptacles a much paler yellowish brown. 



Specific characters of male. — The accessory sexual apparatus of the male is complicated ; the posterior 

 flap on the second legs is roughened and armed with short spines; the peg on the fourth legs has an 

 accessory peg distal to itself, which is solid and is not connected with the receptacle inside the first 

 peg; the boot-shaped flap on this leg has no heel. 



On the third legs a long slender and flattened process extends outward from the anterior margin of 

 the ventral surface of the basal joint, parallel with the axis of the leg. Its tip is curved upward around 

 the end of the second basal joint and often extends back toward the body on the dorsal surface. Above 

 this process, on the anterior margin of the dorsal surface of the second joint, are two peculiar structures. 



