PARASITIC COPEPODS — WILSON 553 



female and are similarly removed some distance from the anterior 

 margin and are widely separated. The abdomen is acorn-shaped, 

 contracted into a short neck where it joins the thorax and then abruptly 

 widens until the width equals the length. The posterior sinus is one- 

 fourth of the length and the caudal rami are subterminal. The paired 

 testes are elongate-elliptical and do not quite reach the base of the 

 posterior sinus. Their anterior ends are tapered into the ducts lead- 

 ing to the vesicle and the posterior ends are bluntly rounded. 



The first and second antennae are almost exactly like those of the 

 female; the claw on the second segment of the first antenna is near 

 the posterior margin. On the ventral surface of the proximal seg- 

 ment of the second antenna close to its base are two unequal spines. 

 The supporting ribs in the margin of the sucking disks are shown in 

 figure 36 ; they are well separated and each is made up of three rather 

 indistinct segments, the terminal one enlarged at its proximal end. 

 The teeth of the marginal fringe are much wider at the base than in 

 the female. The maxilliped (fig. 48) is considerably stouter than 

 that of the female, especially in the three terminal segments, but the 

 terminal claw is no larger. The first two pairs of legs have flagella, 

 the third leg is shown in figure 38 ; the proximal basipod segment has 

 a short and acute spine at its posterior distal corner and the distal 

 basipod segment has a large sac opening on its posterior margin. The 

 rim of the opening is thickened and produced into two finger proc- 

 esses on the ventral side near the basipod. In the fourth leg (fig. 39) 

 the lobe on the basal segment is larger than the entire basipod and 

 in dorsal view projects beyond the lateral margin of the abdomen and 

 is densely fringed with hairs. The second segment has a pointed 

 process at its anterior distal corner, which curves forward and outward 

 and has an acuminate tip. Total length, 7.50 mm. 



Remarks. — The exceptionallj^ large posterior lobe on the proximal 

 segment of the fourth basipod is the most prominent characteristic of 

 this male. Coupled with the brown spots distributed over the entire 

 dorsal surface of the body it will furnish a ready means of identifica- 

 tion. The large number of specimens obtained from Trichopodus 

 pectoralis suggests that it is the real host of this copepod. 



ARGULUS INTECTUS, new species 



Plate 22, Figures 40-47 



One female and one of the three males of this new species, obtained 

 from the outside surface of a scup (Stenotomus chrysops) at Woods 

 Hole, Mass., are the holotype and allotype of the new species, U.S.N.M. 

 No. 78891. 



Female. — Carapace elliptical, one-tenth longer than wide and 

 broadly rounded both anteriorly and posteriorly. Posterior lobes 



