NO. 1573. PARASITIC COPEPOD:^ WILSON. 347 



i. Free thorax segments -n-ider than long: second segment the longest, with 

 small lateral wings: alidomen two-jointed, terminal joint the larger. 



Pcrissopus Steenstrup and Liitken, 18(il. p. .352. 

 k. Exopods only three-jointed: fourth segment lunate, fitting down over 



the genital segment Echthrogaleus Steenstrup and Liitken, 1861. p. 362. 



1-. Both rami three-jointed : fourth segment orbicular, not overlapping the 

 genital segment Dinemaiiira Latreille. 1829, p. 374. 



PHOLIDOPUS, nevs^ genus name. 



Lepidopus Dana, 1852, p. 1373. pi. xcv, figs. 5 a — k. 



Perissopus Steenstrup and Lutken, 1861, p. 394 ipart i, — Bassett-Smith, 1899, 

 p. 468 (part). 



Female. — First thorax segment joined with the head to form the 

 carapace, which is subquadrangiilar and widest posteriorly. Second 

 and third thorax segments fused, and furnished with a single pair of 

 large, rounded dorsal plates. Fourth segment free and armed ^^-ith 

 a similar pair of dorsal plates. Genital segment wider and longer 

 than the carapace, its posterior margin bilobed. the two halves evenly 

 rounded like the two pairs of dorsal plates on the free segments. 

 Abdomen minute, attached to the ventral surface of the genital seg- 

 ment some little distance in front of the posterior margin, so as to 

 be wholly concealed in dorsal view. Anal laminae short, tipped with 

 small spines. Frontal plates well differentiated and larger than in 

 the other Pandarina^. Second antenna^ three-jointed and uncinate, 

 the terminal hook considerably longer than the basal jomts, sickle- 

 shaped and armed with two rows of teeth along its inner margin. 

 ^h)uth-tube long and slender, as in Pandarus; mandibles with a 

 straight tip, and the inner margin serrulate. Second maxillie close 

 to the base of the mouth-tube, composed of tw(^ short, well-rounded 

 joints terminated by a small and nearly straight spine. Termmal 

 joint of second maxillipeds widened and flattened into a broad lamina, 

 covered with scales on its ventral surface, each scale terminating in 

 a minute spme. First swimmmg legs slender, uniramose, and three- 

 jointed, the terminal joint armed with five short setae. Second, third, 

 and fourth sN\'imming legs biramose ; second pair with slender basal 

 segments and two-jointed rami; tliird and fourth pairs with the basal 

 segments broadly lamellar, and the rami minute, rudimentary, one- 

 jointed processes attached to the posterior edges of these lamellag; 

 setae all very short. Xothmg is kno\\Ti of the egg cases or eggs. 



Male. — Unknown . 



(Pholidopus, (l)oXi5, a scale, and rrov;, foot.) 



The new name given above is suggested in place of Dana's Lepidopus, 

 which was preoccupied in 1770 by Gouan for a genus of fishes. That 

 tliis is a valid genus and not a sjmonym for Perissopus, as suggested 

 by Steenstrup and Liitken in 1861, by Brady in 1883, and again by 

 Bassett-Smith in 1899, can be readily seen by the following com- 

 parison : 



