572 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 94 



amcricambs and the boss on the basal plate are armed with stout scale- 

 like spines but in macvlosm the spines are small and simple and there 

 is no boss on the basal plate. 



The respiratory areas in these two species are so nearly alike yet 

 differ so much among themselves that sufficient search miglit yield a 

 specimen of each species in which these areas could be regarded as 

 identical. During the search it would become evident that the areas 

 show definite tendencies toward the two forms in figures 23 and 24. 

 Figures 29 and 30 show the accessory sex characters in the last three 

 pairs of legs in the two males. Without giving a detailed comparison 

 it can be seen readily that nowhere do they correspond; that every- 

 where there are marked differences. Finally it is worthy of note 

 that newly hatched larvae of these two species have been obtained 

 from eggs laid in aquaria in the laboratory. These larvae have 

 been fully described and figured (Wilson, 1907b, p. 416, pi. 31, figs. 

 15-32, maculosus, and 1904, p. 639, figs. 16-21, americanus). The con- 

 trast between the respiratory areas in these two larvae is especially 

 interesting, as it strongly offsets whatever similarity may be found 

 in the adults. 



There is thus a single characteristic in which more or less similarity 

 might be claimed but everywhere else there is such overwhelming 

 dissimilarity as definitely to separate the species and make them both 

 valid. 



ARGULUS DrVERSUS.'o new name 



Argulus maculosus Meehean, 1940, p. 507, fig. 40, preoccupied. 



The characters given in the key on p. 579 distinguish this species 

 from its nearest relatives. 



ARGULUS PAULENSIS Wilson 



PiATE 21, Figures 31-33 



Arffulus paulensis Wrr.soN, 1924, p. 4, pi. 1, figs. 1-5. 

 Argulus salminei Meehean, 1940, p. 502 (part). 



Although admitting that the National Museum collection contained 

 no specimen of salminei with which to compare this species, Meehean 

 (1940, p. 468) nevertheless decided that the two species were "appar- 

 ently the same" and recorded paulensis as an actual synonym of 

 salminei. The types of both sexes of these species were reexamined 

 and the following details are now added to the original description: 



Female. — Abdomen longer than wide with broadly rounded pos- 

 terior lobes, which are fringed with short hairs. The posterior sinus 

 is a quarter of the abdomen length and the caudal rami are curved 



^'' diversus, different. 



