2 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.64. 



NEW SPECIES AND A NEW GENUS. 

 ARGULUS NOBILIS, Thiele. 



Plate 1, figs. 6-9. 



Argulus nobilis Thiele, Mittheilungen aus dem Zoologischen Museum zu 



Berlin, vol. 2, Heft 4, p. 28, pi. 7, figs. 64-66 ; pi. 8, figs. 67-76, 1904. 

 Argulus ingens Wilson, Proceedings U. S. National Museum, vol. 42, 1912, 

 p. 233, pi. 30, figs. 1-6 ; pi. 31, fig. 7. 



Host and record of specimens. — The New York aquarium secured 

 from Lake Calcasieu, Louisiana, about two years ago a colony of 

 alligator gars, Lepisosteus tristoechus, and kept tliem on exhibition 

 for a long time. They became so badly infested with the above 

 species of Argulus that it was necessary to take the fish out of their 

 aquarium and remove the parasites. The latter were preserved and 

 sent to the author for identification; they included adults of both 

 sexes and various developmental stages. The amount of material was 

 sufficient to make possible the identity of the two species indicated 

 above. 



Thiele had but seven specimens, including a single male, when the 

 species was originally described, while the present author had one 

 male and two females upon which to found the species ingens. Be- 

 tween the species as described and figured there were substantial dif- 

 ferences. But the large number of specimens in the present material, 

 and especially the developmental stages, forms a series that passes 

 into nohilis on the one hand, and into ingen^s on the other. We are 

 forced to conclude therefore that the two forms are simple variations 

 of one and the same species, and if so, Thiele's name takes precedence. 

 Such a conclusion was suggested by the present author in 1916,^ 

 but at that time there was no basis of actual proof. The two de- 

 scriptions with their accompanying figures may be accepted as pub- 

 lished, each for its own variety. The one presented by Thiele may 

 then be known as Argulus nohilis, variety nohilis, and the one by 

 the present author as Argulus nohilis, variety ingens. 



In the present paper developmental stages are described and figured 

 for the first time. 



Color. — Thiele stated that his specimens were faintly tinged with 

 brown, but when alive were probably transparent. The color of 

 ingens (preserved material) was given as a uniform yellowish-brown. 

 The. present material shows a few specimens that are almost trans- 

 parent, others that are yellowish-brown, and still others that are 

 dark cinnamon-brown. The general impression of a hundred speci- 

 mens spread out dorsal side uppermost is a dark shade of brown. 



* Bulletin. Bureau of Fisheries, vol. 34, p. 354. 



