﻿188 PROCEEDINGS OF THE NATIONAL MUSEUM vol. lOo 



contributions from this paper are noteworthy. He pointed out (1) 

 the branching of the anterior end of the dorsal ridge on the carapace, 

 and how it could be made clear, and (2) the striking similarity be- 

 tween A. trilineatus and A. foliaceus in all details of characters except 

 the slight difference in the armature of the second leg of the male. He 

 suggested that the American species was derived from European 

 origin. Three years later, Meehean (1940) decided that the specimens 

 from Louisiana as well as those of Guberlet and Wilson were referable 

 to A. japonicus. He based this conclusion on a comparative study of 

 specimens of A. japonicus that Wilson lent him and examples of the 

 same species from Tokioka and Watanabe in Japan and A. S. Pearse's 

 material. It is apparent that A. japonicus from Japan and the United 

 States is a very variable form. The difference between extreme speci- 

 mens appears greater than that between this species and A. foliaceus, 

 a supposed indigenous European form. Wilson (1944) maintained 

 the validity of his species A. trilineatus and referred to it more speci- 

 mens that Meehean described in 1937 and 1940 as A. japonicus. He 

 redescribed the male, the allotype of A. trilineatus, and emphasized 

 the following features : 



(1) Pattern of dorsal ridge (or groove) on the carapace, which is 

 not forked anteriorly. 



(2) Length of the posterior lobe of the carapace, which reaches 

 only to the anterior margin of the fourth thoracic segment in the 

 male, but well beyond the base of the abdomen in the female. 



(3) Details of the second antenna, which has only one large basal 

 joint and two distal ones instead of being 4-jointed as in Thiele's or 

 6- jointed as in Wilson's own description of A. japonicus. 



(4) Supporting ribs of the sucking cups are in four segments. 



(5) Male maxilliped (Thiele's hind maxilla) has its distal joint 

 divided longitudinally. 



(6) Caudal rami subbasal in the anal sinus, which ends anteriorly 

 in a triangle. 



(7) Absence of flagella on the first and second legs, so resembling 

 Wilson's A. japonicus but differing from the specimens of Tokioka, 

 Guberlet, and Meehean, who described such flagella. 



"The sum total of these differences is more than sufficient to over- 

 come any similarity that may be found in the pattern of the respiratory 

 area" and would preclude this form's being placed under A. japonicm. 



Through the courtesy of the U. S. National Museum, three females, 

 one male, and one immature specimen of A. japonicus have been sent 

 to us for comparison. They are from a lot of 75 argulids and labeled 

 "#69835, skin, goldfish, Tokyo, Japan, June 10, 1929, Taku Komai 

 Coll., Id. C. B. W." These differ from Wilson's own description of 

 this species (1944) in the following characters : 



