NO. 1573. PARASITIC COPEPODS— WILSON. 455 



they are not likely to be the two sexes of the same species, and we find 

 that their anatomy confirms such a conclusion. 



The shape of the grooving of the carapace in the Nogaus form is 

 radically different from that in the female of Echthrogaleus coleoptratus, 

 and also from that of such of the males of this genus as are known. 

 Tlie fourth and genital segments are also very dift'erent from those in 

 Echthrogaleus males in their relative size and shape. The second and 

 third legs have only two joints in the exopods, while the rami of the 

 fourth legs are one-jointed. The second maxillipeds are much 

 swollen and are armed wdth short curved claws and corrugated 'knobs. 



In all these particulars and in its size the species corresponds closely 

 with Nogagus cselehs and Nogagus elongatus, and may therefore be tem- 

 porarily assigned a j)lace in the genus Perissopus instead of Echthro- 

 galeus. 



NOGAGUS MURRAYI Brady. 



Nogagus murrnyi Brady, 1883, p. 136, pi. lv, fig. 1. 



Brady's description in the Report on the Copepoda of the Challenger 

 Expedition is as follows: 



Length, 4 mm. Cephalolliorax ovate, much longer than broad and nearly twice as 

 long as tlie abdomen; frontal margin rounded, lateral margins somewhat sinuous, pos- 

 terior angles moderately produced backward and rounded off. First abdominal (gen- 

 ital) segment about as long as broad, margins round; angles not at all produced nor 

 acute. Two posterior abdominal segments much broader than long, the last pentagonal . 

 in shape, and produced backwards between the caudal lamellte into two obtuse points; 

 caudal lamellse about as broad as long, sulxjuadrate, each bearing four finely plumose 

 setse. 



Taken in the open sea off Rio de Janeiro, and in the North Atlantic (about lat. 25° N.), 

 April 28, 29, 187(5. Very similar to Nogagus errans Kroyer, which, however, differs 

 decidedly in the shape of the last abdominal and two posterior thoracic segments. 



In the figure which accompanies this description and which is 

 labeled "Adult female (?) seen from below," only two pairs of legs 

 are shown, the third and fourth pairs, in both of which the rami are 

 represented as one-jointed. No adhesion pads are shown at the 

 bases of either pair of antennse, nor anywhere else on the ventral 

 surface. The mouth-tube is short, broad, and well rounded at the 

 tip, and there is a very well-defined furca on the mid-line between 

 the bases of the second maxillipeds. 



These last details, if reliable, prove that the copepod is not a 

 Nogaus at all, hut one of the Euryphorina^, resembling, perhaps, the 

 genus Dysgatnus more tlian any of the others. 



