PARASITIC COPEPODS — ^WILSON 567 



those of the female, a small elliptical anterior area and a large pos- 

 terior area slightly curved. The abdomen is spindle-shaped, one- 

 half longer than wide ; the posterior sinus does not reach the center 

 and the posterior lobes are bluntly rounded. The base of the sinus 

 is angular and the caudal rami are subbasal, attached to the sides of 

 the angle a short distance from the extreme base. (See fig. 80.) 



The first and second antennae are like those of the female; the 

 supporting rods in the margins of the sucking disks are stout and 

 4-jointed. The basal segment is twice as long as any of the others 

 and is tapered proximally ; the other segments diminish in size distally. 

 The segments of the maxillipeds are much shorter than in the female 

 and tlie end segment is divided lengthwise, the anterior portion ending 

 in a finger process, the posterior portion in a curved claw. The first 

 and second legs have no flagella ; in the second legs the proximal basi- 

 pod segment has a rounded knob at either end extending backward 

 from the posterior margin and the two knobs are connected by a con- 

 cave membrane. In the third legs the distal basipod segment has a 

 large inner receptacle that opens on the posterior surface and can be 

 closed by an external flap. The proximal basipod segment of the 

 fourth leg has a rounded lobe on its posterior margin ; the distal basi- 

 pod segment has an acutely pointed peg at its distal anterior corner, 

 and its posterior margin is fringed with long hairs. Total length, 

 3.25 mm. Carapace, 2.15 mm. long, 1.95 mm. wide. 



Reviarks. — With reference to this species Meehean said (1940, p. 

 468) : "Specimens of A. japonicus collected by Dr. Pearse in Japan and 

 those sent me from that country proved to be identical with A. frilin- 

 eatus, thus invalidating another species." The fortunate discovery 

 of the male suffices to distinguish trilineatus from japonicus. A fine 

 lot of specimens of japonicus., including both sexes, was taken from 

 goldfish at Tokyo, Japan, and sent to the National Museum. For 

 the sake of comparison with the present species these are fully described 

 on p. 559 and figured. If the two sets of figures here presented are 

 compared in detail it will be found that they are not identical, as 

 Meehean claimed, but enough differences can easily be found to make 

 both species valid. Attention is called particularly to the pattern 

 of the dorsal grooves of the carapace, to the length of the posterior 

 lobes, to the details of the first and second antennae, especially the 

 latter, to the supporting rods of the sucking disks, to the maxillipeds, 

 and to the caudal rami. The sum total of these differences is more 

 than sufficient to overcome any similarity that may be found in the 

 pattern of the respiratory areas. 



