566 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 94 



In the first antennae there is a well-developed claw on the anterior 

 margin of the second segment, the lateral claw is long and slender and 

 its curve nearly reaches the tip of the flagellum, which is 3-segmented. 

 The second antenna is 4-segmented, the basal segment a little longer 

 than the other three segments combined and armed on its ventral 

 surface with a large acute spine. The sucking disks are small, well 

 separated, and removed a considerable distance behind the compound 

 eyes. The supporting rods are very irregular, each made up of 

 about 35 segments more or less imbricated, of different lengths and 

 different curvatures, no two alike but showing a general tendency 

 toward a uniform taper distally (fig. 91). The maxilliped cor- 

 responds well with the California specimens and is distinguished 

 chiefly by the finger processes with which it is tipped (fig. 93). The 

 first two pairs of legs have flagella and the fourth basipod has a boot- 

 shaped posterior lamella. Length, 8 mm. 



Remarks. — The description of this Thailand specimen is of interest 

 chiefly to show the differences that may occur within the same species 

 in specimens living in widely separated localities. The supporting 

 rods of the sucking disks are worthy of special comment for the 

 variations they exhibit. In the original type specimens from Cali- 

 fornia each was made up of 19 to 21 crescentic disks regular in out- 

 line, uniformly imbricated, and tapered distally. In this specimen 

 from the other side of the Pacific the number of segments jumps to 

 30 or more and the only regularity left is in the distal tapering, the 

 form and the imbrication becomingly extremely irregular. 



ARGULUS TRILINEATUS Wilson 



Plate 25, Figukes 79-88 



Argulits trilineata Wilson, 1904, p. 651, figs. 34-38. 

 Argulus japonicus Meehean, 1940, p. 494, fig. 32. 



This species was founded upon a single female from a goldfish 

 from Macon, Ga., and another single female was obtained from a 

 goldfish at Henderson, Ky., in 1914. These are the only specimens 

 reported up to June 1937, when 6 females and 6 males were taken by 

 Dr. Josiah Bridge from goldfish at Takoma Park, Md. The males, the 

 allotypes, U.S.N.M. No. 78900, are the first males to be collected. 



Male. — Carapace elliptical, a little shorter than wide and reaching 

 just beyond the anterior margin of the fourth thoracic segment. The 

 cephalic area projects considerably from the anterior margin; the 

 compound eyes are large, far forward, and well separated. The pos- 

 terior sinus is quite narrow and only about a fourth of the carapace 

 length. The central longitudinal ribs extend to the frontal margin 

 of the head and are not branched. The respiratory areas are like 



