440 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxm. 



The genus was very poorly described by its author and by the others 

 who immediately followed him, and to this defect, no doubt, is partly 

 due the confusion which has ensued ever since. 



Leach's description is as follows: 



Deux courtes soies a le queue, portant plusieurs styles a leur extremite: les trois 

 premieres pieces de rabdomen ont les cotes arrondis, tandis que le quatrieme et le 

 cinquieme les ont termines en pointe: tet en forme de fer a cheval (1819, p. 535). 



Desmarest in 1825 copied Leach's description, but made a curious 

 blunder in endeavoring to explain the ''deux courtes soies." 

 For he wrote in his genus diagnosis of Nogaus: 



Deux courtes soies ou tubes oviferes a la queue, portant plusiem-s styles a leur 

 extremite (p. 340). 



Egg-tubes carrying styles at their tip would be an anomaly indeed. 

 Burmeister repeated this blunder in 1833 by declaring: 



Ausserdem gehoren noch die beiden von Desmarest erwahnten Gattungen 

 Nogaus Leach, und Riscvlus Leach, heigher (Caligina), welche sich durch Anhange 

 am Ende der Eierhalter von alien unterscheiden (p. 331). 



These mistakes become doubly ridiculous when we remember that 

 Leach's original specimen, which as yet remained the only one de- 

 scribed, was a male. 



Only a few details were added by other writers and even so good a 

 systematist as ]\Iilne Edwards was content to say when defining 

 this genus in his great work on the Crustacea published in 1840: 



II est carecterise principalement par la structure des pates posterieures, lesquelles, 

 au lieu d'etre simples et subambulatoires comme chez les Caliges, sont l)iramees et 

 natatoires comme celles des paires precedentes (p. 459). 



As though this were not common, also, to every genus of tlie Pan- 

 daring. Indeed Milne Edwards himself, in describing the genera 

 of the Pandarinaa, states under nearly every one, "Les pates sont 

 conformees comme chez les Nogagues." 



He then adds under Nogagus: 



Le thorax se compose de quatre grands articles Ijien distincts; et le premier de 

 ces articles (correspondant au second anneau thoracique, le premier anneau etant 

 toujours confondu avec la tete) presente de chaque c6te un petit prolongement lamel- 

 leux. Enfin, les deux petites lames natatoires qui terminent I'abdomen sont un peu 

 plus developpees que chez la plupart des Caligiens (p. 459). 



In making this last statement he substituted one error for another; 

 the anal laminf? are most certainly not "tubes oviferes," as he 

 recognized, but neither can they be regarded as "lames natatoires." 



With regard to their size he evidently failed to consider the fact 

 that he was speaking exclusively of males. The anal laminae in this 

 sex are always larger than in the females, and those possessed by 

 Nogaus species are no larger than would naturally be expected. 



