450 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxiii. 



NOGAGUS CALEBS Heller. 



Nogagus axlchs Heller, 1865, p. 208, pi. xx, lig. 4. 



like the preceding, only a single description of this species has 

 ever been published, but that was so accurate, and the figures accom- 

 panying it so clear, that we have little difficult}^ in locating the species 

 in the genus Perissopus. 



It shows distinctly the narrow lateral lobes of the carapace, sep- 

 arated from the central portion by well-defined grooves; the char- 

 acteristic conspicilla almost touching each other on the mid-line 

 near the frontal plates; the short and very wide second thorax 

 segment, with its lateral lobes directed backward; the third and 

 fourth segments diminishing in width but increasing in length, the 

 wide and short, one-jointed abdomen with large anal lamina\ 



The mouth-parts and maxillipeds are very similar to those in the 

 female Perissopus, while the details of the swimming legs are almost 

 identical with those of the latter species. 



The only dift'erence is found in the genital segment, which is trape- 

 zoidal, widened posteriorly with rounded angles, each armed with a 

 large spine and a seta. But this may well be a specific difference 

 and only serve to emphasize the resemblances. 



The species is rather small (4 mm. long) for either Pandarus or 

 Nesvppus, but is just right for the genus Perissopus, where it undoubt- 

 edly belongs. 



PANDARUS CRANCHII (Nogaus male) Beneden. 



Pandaras cranchii Beneden, 1802 a, p. 221, pi. i, figs. 1-5. 



In the same paper in which he descrihed Pandarus ajfinis (see p. 444) 

 Beneden also presented a Nogaus form which he claimed to be the 

 male of Pandarus cranchii. Although the description in the text is 

 no better than for affinis, yet the author has given for this species a 

 view of the ventral surface, showing all the appendages. From this 

 we can gather enough data to show clearly, in connection with the 

 general body form, that the copepod is not a Pandarus at all, but 

 belongs either to the genus Nesippus or Perissopus. The carapace is 

 narrow and elongated, with narrow posterior lobes, and without 

 accessory lobes ; the three free segments and the genital segment are 

 all about the same width; the latter is very small and shows no traces 

 of legs on its sides or posterior corners; the abdomen is one-jointed, 

 very small and triangular, and is armed with small and triangular 

 anal laminae; the second maxillipeds are armed with forceps knobs 

 and not with claws; the rami of the fourth legs have but a single 

 joint. 



Further along in the same paper Beneden describes what he calls a 

 new genus, and to which he gives the name OMamys incisus; Bassett- 



