BEVIEW OF GENUS ARGULUS — MEEHEAN 467 



On the second maxillae the teeth of the basal plate and the two 

 pairs near the midventral line of the body may be characteristic 

 in shape, size, or number. 



Finally, the presence or absence of flagella on the swimming ap- 

 pendages, the shape of the swimming lobes on the posterior of the 

 fourth appendages of the female, and other more variable characters 

 may be used at times. 



The maximum size as reported for each sex is given. Mature speci- 

 mens of either sex within a species may vary considerably in this 

 respect, and the sex difference may be great or small. Relative body 

 proportions are not a reliable index for specific determination, since 

 the proportions may change according to size, age, and stage of 

 development. In a general way they do hold for sex comparisons; 

 that is, the carapace may extend farther posteriorly on the male, or 

 the length and width of abdomen or its shape may be different on the 

 two sexes, etc., but on the whole they cannot be relied upon to estab- 

 lish specific identification. Color has been used in many instances, 

 but it too cannot be depended upon as the sole basis or even in combi- 

 nation with proportional measurements for specific determination. 

 All species are American fresh- water forms unless otherwise desig- 

 nated. All figures used are from camera lucida drawings of specimens 

 in the National Museum and from the t3'pes where practicable. 



SYNONYMY 



Certain of the species listed in the literature have proved to be 

 synonymous when studied according to the characters outlined for 

 specific indentification. A. iiram.'Osus Bere (1931) is identical with 

 appendiculosus Wilson (1907). Any differences are merely a mat- 

 ter of size. A. ingens Wilson (1912b) is the same as nohilis Thiele 

 (1904), as previously stated by Wilson (1924), but there seems to be 

 no reason for maintaining a variety as he has done. A. canadensis 

 Wilson (1916) is the same as A. stizostethii Kellicott (1880). There 

 are no flagella on the latter, contrary to Wilson (1902), and he failed 

 to note the complete respiratory area. 



The male of A. niger has never been described, since it is the same 

 as pugettensis except that the former is very dark, as its name 

 indicates. 



Vial 77810 (old number 60589) in the National Museum contains a 

 male labeled pugettensis that is entirely different from the described 

 male of that species and is from Key West, while the species has 

 always been reported on hosts indigenous to the Pacific coast. This 

 specimen has been given the new name floridensis. It was collected 

 by A. E. Verrill and dated 1884. 



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