PARASITIC COPEPODS — WILSON 551 



The first antennae are small and 3-seginented, each segment armed 

 with tiny setae; the second antennae are prehensile and dispropor- 

 tionally large, each tipped with a strong curved claw having an 

 accessory spine on its inner margin near the base. Mouth parts small 

 but of normal shape and not at all like the nondescript processes in 

 Paeon. There are four pairs of biramose legs spaced as in figure 187, 

 the first pair just behind the head and the last pair just in front of 

 the posterior end of the body, the spaces between pairs in the propor- 

 tions 5:4: 1.50. The rami are 1-segmented, and the exopods and 

 endopods are about the same length. Total length, 3.15 mm. Width 

 of head, 1 mm. 



Male. — A pygmy male was fastened so securely to the ventral sur- 

 face of the third thoracic segment of the female that the two could 

 not be separated without very serious mutilation. Consequently it was 

 deemed wise to leave them intact and to be satisfied for the present with 

 the knowledge that the male is a pygmy attached to the female, as in 

 other genera of the Sphyriidae. 



Suborder Arguloida 

 Family ARGULIDAE 



Genus ARGULUS Muller, 1875 



During the preparation of this paper an article on the genus Argulus 

 by O. Lloyd Meehean (1940) was published. This article added many 

 valuable data to our knowledge of the Argulidae, especially with 

 reference to the respiratory areas and the supporting rods of the suck- 

 ing cups. Upon these two features, combined with the accessory sex 

 characters of the legs of the male, Meehean established a key to the 

 species of the genus. Such a key has been greatly needed for a long 

 time, and if this one be supplemented with the structural characters 

 of the various appendages its usefulness will be increased. I have 

 therefore incorporated these characters in Meehean's key, which I have 

 added as a supplement to this paper (p. 576). As it stands in 

 Meehean's paper, however, too much specific value has been placed 

 upon the areas and rods and not enough upon other structural char- 

 acters, with the result that formerly accepted species of ArguJus have 

 been reduced to synonyms. A discussion of the validity of these 

 species makes up the remainder of the present paper. Such a dis- 

 cussion is quite appropriate, since this paper is so largely concerned 

 with species belonging to the genus Argulus. 



The removal by synonymy of as large a number of species of 

 Argulm as advocated by Meehean constitutes a serious encroachment 

 upon the genus. Consequently the mere statement that one species 

 is the synonym of another is not sufficient. Actual proof must be 



