NO. 1573. PARASITIC COPEPODS— WILSON. 849 



jointed, and concealed beneath the genital segment; mouth- tube, ap- 

 pendages, and adhesion pads similar to those in other Pandarids. 



Male. — Unknown. 



{Lejnmacrus, XsttIs, a scale, and j.iaKpog, long, referring to the 

 long and narrow dorsal plates on the genital segment.) 



Genus DEMOLEUS Heller. 



Caligus paradoxus Otto, 1828, p. 352, pi. xxii, figs. 5, G. 



Nofjagiwi grandis Steenstrup and Lutkex, 1861, p. 386, pi. x, fig. It. 



Demoletts paradoxus Heller, 1865, p. 199, pi. xix, fig. 3. 



In 1828 Otto described the male and female of a new species of 

 copepod parasite which he named Caligus paradoxus. The male had 

 the t}'7:)ical Nogaus form, but was much larger than other species, 

 being 12.5 mm. in length. In 1865 Heller rediscovered the female 

 of Otto's species and made it the ti^e of a new genus, wliichhe called 

 Demoleus, and for which he gave the following genus diagnosis: 



Cephalothorax emarginate posteriorly, two following segments free, fourth segment 

 with dor.=!al plates (in the female); frontal plates prominent, first antennae partly con- 

 cealed by them, two-jointed. All the legs biramose, rami two-jointed, armed with 

 plumose setae, those of the first and fourth pairs minute, of the second and third pairs 

 lamellar and enlarged. Genital segment elongate, abdomen very short, not jointed, 

 covered with a foliaceous dorsal lamina, appendages large. Male of the tj^^ical Noga- 

 gu3 form. 



With this description and the excellent figures published by Otto 

 and Heller to guide us we can locate in this genus the form Nogagus 

 grandis, described by Steenstrup and Ltitken in 1861 from two 

 specimens obtained in the warmer portion of the Atlantic, the definite 

 locality and host not given. At the conclusion of their description 

 these authors suggest: ''If Dinematura ferox and Nogagus grandis 

 could be proved to come from the same localitj^ they might well be 

 the male and female of the same species" (p. 387). 



But in this they are mistaken, because neither the carapace, the 

 fourth thorax segment, the swimming legs, nor the abdomen corre- 

 spond with those found in Dinematura males, for the carapace in 

 Dinematura is wider and its lateral margins are more strongly convex; 

 the third segment is considerably larger, and the fourth segment car- 

 ries a pair of rudimentar}* dorsal plates, which are entirely lacking m 

 this Nogagus. The genital segment is relatively much wider in 

 Dinematura, and has no posterior lobes; the abdomen is very much 

 narrower and two-jointed, with the joints equal. But the essential 

 difference is found in the swunming legs; in Dinematura males the 

 rami of the second and third pairs are three-jointed like those of the 

 female, while here in Nogagus grandis all the rami are two-jointed. 



Furthermore, a careful comparison of this species \\'ith Otto's tj^e 

 male of Caligus paradoxus show the two to be identical. 



