PARASITIC COPEPODS — WILSON 571 



original description." However, he did not redescribe the original 

 material, but substituted new types, a new description, and new 

 figures, and should have given it a new name; ArgvZus diversus is 

 here proposed, p. 572. His species, therefore, cannot be entered above 

 under the original name; neither should the above references appear 

 over his description of maoulosus as that is an entirely different 

 species. 



Meehean found a vial containing two males and three females in 

 the National Museum collection correctly labeled A. macvlosus. On 

 examination he found the respiratory areas of these five specimens 

 similar to those of A. ainericanu^ and he identified them with that 

 species. However, these specimens are not ainericanus as is plainly 

 shown below. Even if they had been americanus the name macvZosus 

 had the right of priority and the former should have become the 

 synonym. The two species were established in the same publication 

 (Wilson, 1902), maciilosus on p. 715 and americamis on p. 718. 



Meehean (1940, p. 468) apparently believed that this species was 

 established on the basis of color, but in the original description the 

 color was expressly stated to be that of alcoholic specimens, which 

 would nullify any specific value. As might have been easily inferred 

 the color was introduced solely to explain the origin of the specific 

 name. 



The first proof of the validity of both species is found in the shape 

 and proportions of the body regions. In macidosus the carapace falls 

 considerably short of the anterior margin of the abdomen and the 

 inner margins of the posterior lobes are parallel and separated 

 enough to disclose the entire thorax. In americanus the carapace 

 reaches the center of the abdomen and its posterior lobes are turned 

 inward and overlap on the midline, entirely concealing the thorax. 

 In maculosus the abdomen is a fourth as wide as the carapace and as 

 long as it is wide. In americanus the abdomen is half as wide as the 

 carapace and its width is 60 percent greater than its length. In 

 maculosus the caudal rami are definitely subterminal ; in americanus 

 they are more nearly terminal. 



The anterior margin of the first antenna is armed with a stout claw 

 in arnericanus (fig. 25) and the flagellum projects far beyond the 

 curve of the lateral claw. In maculosus (fig. 26) the anterior margin 

 is smooth and the flagellum does not reach the curve of the lateral 

 claw. The second antenna is 4-segmented in americanus and reaches 

 far beyond the tip of the first antenna. In maculosus it is 5-segmented 

 and does not quite reach the tip of the first antenna. Figures 27 and 

 28 show the supporting ribs of the sucking cups in the two species. 

 In each they are 2-segmented but the segments themselves differ radi- 

 cally in length and shape. The ventral surface of the maxillipeds in 



