558 PROCEEDINGS OF THE NATIONAL MUSEUM vol. a* 



having neither heel nor toe. Total length, 5 mm. Carapace, 3 mm. 

 long, 2.95 mm. wide. 



Male. — Carapace orbicular, not narrowed anteriorl}', a little wider 

 than long and reaching only the fourth segment. Cephalic area 58 

 percent of the carapace length, the eyes larger than in the female and 

 farther forward. The respiratory areas are similar but the dividing 

 space between them is diagonal rather than horizontal. The four 

 thoracic segments are the same width and the first three are the same 

 leng-th, but the fourth is only half as long as tJie others and its posterior 

 margin is a half circle. The abdomen is elliptical, one fifth longer 

 than wide, with no anterior corners. The testes are 80 percent of the 

 abdomen's length and distinctly lunate, whence the specific name. 

 The posterior sinus is one-third of the length of the abdomen, the 

 tips of the posterior lobes rounded. The caudal rami are lateral, 

 attached to shoulders on the sides of the sinus near its base. 



The antennae are similar to those of the female while the spines on 

 the basal plate of the maxilliped are longer, curved and acuminate 

 (fig. 65). The proximal segment of the basipod of the second leg 

 has two long finger processes on its posterior margin (fig. 63). The 

 same segment in the third leg is swollen posteriorly but otherwise 

 unmodified. In tlie fourth leg the proximal basipod segment has a 

 posterior lamina very much shorter than in the female, and the distal 

 segment has an acute process at its anterior outer corner. Total 

 length, 4 mm. Carapace, 3 mm, long, 3.02 mm. wide. 



Remarks. — After this species had been described and the figures 

 drawn the specimens suffered a severe drying, but the specific char- 

 acters still remain visible. From A. japonicm., which it most resem- 

 bles, this species may be distinguished in the female by the shape of the 

 fourth segment and the abdomen and by the structural details of the 

 antennae, the maxillipeds, the respiratory areas, and the ribs of the 

 sucking disks. In the male the most striking difference is to be found 

 in the distinctly lunat'e form of the testes, curved toward each other 

 with acute ends. 



ARGULUS JAPONICUS Thiele 



Plate 24, Figtjbes 67-73 



Argulus japonicus Thiele, 1900, p. 48 ; 1904, p. 39, pi. 8, figs. 94-98. 



This is properly an Asiatic species that has been imported into the 

 United States along with the influx of goldfish, which have risen 

 rapidly to popularity in recent years. As goldfish have been dis- 

 tributed to aquaria and artificial ponds these parasites have spread 

 with them and have become very common. 



Thiele (1900) founded his new species upon female specimens taken 

 from goldfish at Tokyo, Japan. Later (1904) he obtained supple- 



