NO. 1504. AMERICAN PARASITIC COPEPODS— WILSON. ()71 



despite its attachment to the carapace, possesses considerable freedom 

 of motion. 



2. It would be the only genus in which all the legs were biramose. 

 This objection has greater value when w^e find that the third legs, 

 which are alwa3\s biramose, show a marked resemblance to those of 

 the Euryphorina3, and are very different from those of the Caliginee. 

 Kroyer,^' in his original description of the genus, notes that the first, 

 third, and fourth legs differ markedly from those of the Caligina?. 

 But he says that the second legs correspond in the smallest details 

 with those of Caligus. "Fjerde''' par F0dder er indtil de mindste 

 Detaillen som has Slaegten Caligus.^'' 



His statement would have been more accurate had he substituted 

 the genus Lepeophthe!ras for Callgus. In Caligus the spines on the 

 outer margin of the exopod in these second legs are large and almost 

 invarialjly turn inward and run diagonally across the ramus, while 

 in Lepeophtheirm they are smaller and are parallel with the margin, 

 as we find them here. 



3. The e3^es, which are very small and easil}" overlooked in the 

 adult, are separate, one on either side of the mid-line, and arc not 

 fused, as in the Caligintv. 



4. The mouth tube, while it has not become as long and pointed as 

 in some of the Euryphorin^ {AhMon and Gloiopotes)^ is yet noticeably 

 longer and narrower than in the Caligina?, and is also definitely jointed 

 near the base. The side incisions at the joint are deeper than usual, 

 and the corners are more prominent, as was noted by Kroyer. In 

 short, the mouth and the mouth-parts are as symmetricall,y intermedi- 

 ate between the types of the Caliginae and the Euryphorinse as could 

 well be desired. 



B. On the other hand, if it were included with the Euryphorinffi — 



1. It w^ould still be peculiar in having two free thorax segments and 

 also in the arrangement of the grooves and areas on the dorsal surface 

 of the carapace. While the fusion of the head and thorax segments is 

 not as complete in the Eurj^phorinai as in the Caligina?, it is still thor- 

 ough enough to effectually prevent any such freedom of movement as 

 we find here. 



2. It has no dorsal plates on the free thorax, the genital .segment, or 

 the abdomen. This, of course, would not count for much if it w^ere 

 the only difference, but it does contribute materially in the way of 

 cumulative evidence. 



3. It would be the only genus in which the larva was attached dur- 

 ing the chalimus stage by means of a frontal filament like tho.se found 



«0m Snyltekrebsene, isfer med Heiisyn til Danske Fauna, 1838, pp. 32-34. 

 ''He calls the first maxillipeds the "first pair of legs," and hence his "fjerde," or 

 fourth pair, would be really the second swimming legs. 



