REPORT ON THE COPEPODA. 81 



have both two-jointed. The general characters are those of Temora; rostrum and caudal 

 stylets as figured by Claus. 



Centropages, Kroyer. 



Centrqpages, Kroyer, Xat. Tidskr., 1849. 



,, Boeck, Oversigt Norges Copepoder, 1864. 



„ Brady, Monog. Brit. Copepoda, 1878. 



Catopia, Dana, Proc. Amer. Acad. Sci., 1849. 

 Calanopia, Dana (in part), Crust. U. S. Expl. Exped., 1852. 

 Ichthyophurba, Lilljeborg, De Crustaceis ex. ord. trib., 1853. 

 „ Claus, Die frei lebenden Copepoden, 1863. 



Body elongated; head distinct from the thorax, produced into a cloven rostrum, and 

 more or less distinctly divided by a transverse groove into two segments. Anterior 

 antennae twenty-four-jointed, that of the right side in the male geniculated and pre- 

 hensile. Mandibles, maxilla?, and foot-jaws similar to those of Calanus, except that the 

 setas of the anterior foot-jaws are beset with strong marginal hairs as in Pontetta. The 

 five pairs of swimming feet have both branches three-jointed, except the outer branch 

 of the left fifth foot in the male, which is only two-jointed, while on the right side the 

 outer branch, though three-jointed, forms a doubly-clawed prehensile organ. Eye median 

 and mobile, of moderate size. 



From Pontetta this genus is separated by the single eye, by the Calanoid form of 

 the posterior foot-jaw, the three-jointed inner branches of the swimming feet, and by the 

 peculiar structure of the fifth pair of feet in both sexes. From Diaptomus, Temora, and 

 other nearly allied genera, the characters of the swimming feet, especially of the fifth 

 pair, form a sufficient distinction, while from Canclace it is further separated by the struc- 

 ture of the mouth-organs, more particularly of the mandibles and maxillse. 



The names Catopia and Calanopia were proposed by Dana, the one as a genus, the 

 other as a sub-genus, to include certain species closely allied to Pontetta. The characters 

 relied upon do not, however, appear to be very important, or very serviceable as landmarks 

 of classification, the two species assigned by Prof. Dana to Calanopia (CalctTwpia 

 el/iptica and Calanopia brachiata), belonging, in my view, to two distinct genera. 

 The name Centropages, used by Kroyer in 1849, has precedence, of course, over the more 

 lately published Calanopia and Ichthyophorba, while Catopia, though dating from the 

 same year as Centropages, has not obtained the same currency, and, moreover, has 

 scarcely been defined with sufficient precision. 



Of this genus three European species have been described. Centropages typicus, 

 Kroyer, Centropages hamatus, Lilljeborg, and Centropages violaceus, Claus ; the last of 

 which is by far the commonest representative of the group in the Challenger collection, 

 occurring in at least ten of the surface-net gatherings. But though this one form is very 



(ZOOL. CHALL. EXP. — PART XXIII. — 1883.) & ^ 



