NO. 1504. 



A3IERICAN PAKASITIC COPEPODS— WILSON. 



695 



now decrease in size, become of secondaiy importance, and finally 



assume their adult form (fig. 17). 



These facts with regard to development settle several questions 



which have hitherto been in dispute. 



In the first place the}' fully justify the separation 

 of the genus and its near relatives from the Calig- 

 inte on the one hand and from the Pandarinie on 

 the other, and their establishment as a new sub- 

 family intermediate between these two. 



In the genu>i A/ehion the fourth legs are so rudi- 

 mentary that it is impossible to tell from the mor- 

 phology of the adult whether they are to be 

 regarded as uniramose or biramose. 



Consequent!}" it has been diflicult to locate the 

 genus with any certainty; Heller placed it among 

 the Caliginse, with which it is closely afiiliated in 

 morphology and habits; Gerstaecker placed it in 

 a subfamily which he called the Nogagina as inter- 

 mediate between the Caliginie and the Pandarin^. 

 This latter is the correct position, as the develop- 

 ment proves. The mouth-parts and maxillse are 

 like those of Callgus in early development, but 

 there is no frontal filament, the second antenna3 

 serving in its place. As development progresses 

 the maxillte become broadened and flattened into 

 lamina? (fig. 18) very similar to those of Pandarus^ 

 while the second antennse are reduced to normal 

 size and shape. But the female never degenerates 

 into a fixed form like Pan- 

 darus; on the contrary, the 

 adults of both sexes are fully 



as lively as any Caligus and both swim and 



scuttle about freely. They thus show characters 



belonging to both the subfamilies mentioned 



and constitute a well-defined connecting link 



between them. This is exactly where Ger- 

 staecker has placed them, but there are several 



reasons why his name of Nogagina can not be 



accepted for the subfamily. 



The first objection is to the name itself. The genus Nogagm is 



made up entirely of males belonging to other genera, Pandarus, Nesi]?- 



pus^ Deinoleus, Ecldhrogaleus^ and Dinematura. It has, therefore, no 



right whatsoever to appear as a separate genus, much less to be taken 



as the type of a subfamily. 



Fig. 16.— a chalimus of 

 Alebion glaber just 

 ready to molt into 

 t.he adult stage, 

 showing the fourth 

 segment separated 

 and the fourth leg.s 

 already formed. 



Fig. 17.— The second an- 

 tenna OF AN ADULT MALE 

 OF Alebion glaber. 



