350 BULLETIN OF THE BUREAU OF FISHERIES. 



and which does not reach the margin of the abdomen. The supporting rods of the border of the sucking 

 disks are made up of a basal rectangular section and from four to six barrel-shaped terminal sections, 

 the distal one incomplete and shaped like the letter J, with the stem convoluted. 



Color, a pale yellowish white; the entire digestive canal, including the ramifications of the stomach, 

 a rich creamy yellow, in strong contrast to the white background; eyes dark cinnamon brown; upper 

 surface of the body covered with irregular spots of jet black, thickly sprinkled along the center and over 

 the lateral ramifications of the stomach, but entirely lacking aroimd the eyes and the anterolateral 

 sinuses; semen receptacles yellow, surrounded by a black line. 



Total length, 6 mm.; carapace, 4.35 mm. long, 4.20 mm. wide; abdomen i mm. long and wide. 



(flavescens, yellowish, alluding to the digestive system). 



Remarks. — This is a small and highly colored species and is apparently rather rare, since only the 

 three specimens were found during the entire summer. It may be recognized at once by the prominent 

 yellow lateral lobes of the stomach, the jet-black pigment spots on the dorsal surface, and the compara- 

 tively minute abdomen, with its tiny anal papillae in the enlarged base of the anal sinus. It seems 

 probable that the mud cat is the real host of this species and that the two specimens on the outside of 

 the dogfish were only seeking temporary lodgment. 



Argulus mississippiensis, new species. (PI. lxi, fig. 13-15; pi. LXii, fig. 21; pi. LXin.) 



Host and record of specimens. — Six males and six females were taken by the author from the short- 

 nosed gar, Lepisosteus platoslomus, at Fairport, Iowa, July 17, igi2. They have been given catalogue no. 

 43S7I, U. S. National llluseum. One of the largest females has been selected as the type of the species 

 and has received catalogue no. 43528, U. S. National Museum. This species is found upon the back of 

 the gar's neck just above the dorsal aorta, and there is usually only one parasite on each fish. 



Specific characters oj female. — Carapace about three-fifths of an ellipse, its long diameter transverse; 

 anterior sinuses narrow and deep; posterior sinuses one-quarter the length of the carapace, longer than 

 wide, its sides approximately parallel; lateral lobes very broad, obliquely truncated posteriorly, not 

 quite reaching the abdomen. Eyes comparatively minute and widely separated; respiratory areas 

 placed obliquely at the extreme posterior end of each lobe, the outer area semilunar, its ends consid- 

 erably enlarged and well roimded , the inner area about the same size as one of the sucking disks, inserted 

 on the inner side of the outer area near its anterior end, but separated from it by a considerable interval. 

 Abdomen elliptical , one-fourth longer than wide , and half as long as the carapace ; posterior sinus narrow- 

 triangular, not cut to the center; papillae lateral, near the tips of the lobes; semen receptacles elliptical 

 and close to the midline, their long diameters parallel with the axis of the abdomen. 



^^tennse small and stout; first pair with a medium-sized anterior claw and a long and stout lateral 

 one, the terminal joints linear and not projecting beyond the tip of the lateral claw; second pair with a 

 ventral protuberance on the basal joint just above the basal spine. Sucking disks small, only one- 

 fourteenth the width of the carapace and widely separated ; supporting rods slender and made up of a vari- 

 able number of linear joints; no fringe on the margin. Maxillipeds also small but stout; basal plate 

 projecting far behind the margin of the basal joint and carrying a large lobe distal to the spines; the latter 

 large and acuminate; ventral protuberance small and circular; a roughened plate on the third joint; 

 terminal claws and papillae minute. A pair of small accessory spines between the bases of these maxilli- 

 peds and another larger pair some distance behind the antennae. 



Each of the three posterior pairs of swimming legs carries a ventral lobe fringed with setae on the 

 basal joint; the lobes on the second and third legs are small, that on the fourth legs is much larger and 

 projects beyond the lateral margin of the abdomen ; the second joint of the endopod of the fourth legs 

 also carries a small posterior lobe. There is a small anal papilla on either side of the opening of the 

 oviduct. 



Total length of figured specimen, 15 mm.; carapace, 10 mm. long, 12 mm. wide; abdomen, 4.80 

 mm. long, 3.75 mm. wide. 



Specific characters of male. — The general make-up of the male is similar to that of the female, the 

 carapace lobes slightly overlapping the base of the abdomen; the testes are elliptical and not much 

 larger than the semen receptacles in the female; the basal portion of the anal sinus, proximal to the 

 papillae, is a mere slit, whose sides are in contact or even overlap slightly. The secondary sexual appa- 

 ratus is very complicated and closely resembles that of A . lepidostei. There is a roughened plate, armed 



