560 PROCEEDINGS OF THE NATIONAL MUSEUM vol. o4 



legs the second segment has a large seminal receptacle on the dorsal 

 siu-f ace. Both segments of the basipod of the fourth legs have curved 

 projections on the posterior margin and in addition there is an acute 

 peg at the distal anterior corner of the second segment. As here 

 presented (fig. 73) it reaches considerably beyond the distal end of 

 the segment but can evidently be drawn back by muscles connected 

 with it into the position represented in Thiele's figure (1904, pi. 8, 

 fig. 97). Total length, 3.5 mm. 



Remarks.— X careful comparison of the details in the figures of A. 

 japonicm and of A. lunatus will give evidence that they belong to 

 separate species. There is considerable superficial resemblance but 

 not a single characteristic can be found showing exact correspondence. 



ARGULUS LATUS S. I. Smith 



Plate 27, Figures 108-115 



Argulus latus S. I. Smith, in Verrill and Smitb, 1873, p. 574. 

 Argulus funduli Meehean, 1940, p. 4<J8 (part). 



Smith's type specimens were all females and that is the only sex 

 thus far described. Two males, accompanied by two females, caught 

 swimming freely in the plankton of one of the brackish-water ponds on 

 Chappaquiddick Island off the northern end of Marthas Vineyard, 

 are the first to be discovered and since the previous descriptions of 

 the female have been rather limited a full description of both sexes 

 is here presented. They are U.S.N.M. No. 60452. 



Female.— Car ii])&ce orbicular, 14 percent wider than long, the an- 

 terolateral sinus very shallow, the posterior sinus fully as wide as 

 deep, the posterior lobes broadly rounded and not reaching the center 

 of the third thoracic segment. Fourth segment only two-thirds as 

 wide as the third segment and reduced another third where it joins 

 the abdomen. The latter is obcordate, one-half longer than wide and 

 considerably narrowed posteriorly. The posterior sinus is a little 

 more than one-third the entire length with nearly parallel sides. The 

 caudal rami are subbasal, close to the bottom of the sinus and usually 

 appearing basal owing to the closure of the sinus behind them. The 

 seminal receptacles are proportionally large and elliptical. 



The first antennae have neither a claw nor a knob on the anterior 

 margin of the second segment. The lateral claw is small and weak 

 and its curve reaches only the center of the basal segment of the 

 flagellum. The latter is stout, 3-segmented and the terminal seg- 

 ment is not forked. The second antennae are 4-segmented, the first 

 segment longer than the second and third combined, with a blunt 

 spine on the posterior margin at the base. The compound eyes are 

 far forward and just behind the second antennae; they are of medium 



