444 BULLETIN" 15 8, UNITED STATES FATIOIsrAL MUSEUM 



Distribution. — European seas (Kr0yer, Milne Edwards, Baird, 

 Beneden) ; Mediterranean (Valle, Carus) ; British seas (A. and T. 

 Scott) ; North Atlantic (Brian) ; Table Bay, South Africa (Steb- 

 bing) ; Woods Hole (E. Rathbun, McClendon, Wilson). 



Color. — Body a uniform light yellow, the claws and chitin ribs 

 of the carapace tinged with brown, often becoming quite dark. 



Female. — Carapace trapezoidal ; second and third segments with a 

 knoblike projection on each lateral margin, representing the dorsal 

 plates. Genital segment about the size of the carapace, one-half 

 wider than long, its dorsal plates not curling over ventrally. Ab- 

 domen, including its lateral lobes, as wide as the genital segment, and 



about twice as long as that portion 

 of the latter in front of the base 

 of the abdomen. Egg strings, if 



^^ - ^ . . . . straightened, twenty to thirty times 



i ^^^^ l^ \^ — ^ J the length of the body. Total length, 



18-22 mm. 



Male. — Second segment with lat- 

 eral plate rudiments smaller than 

 in the female, third segment with- 

 out them, both segments very short. 

 Figure 2iQ.—orthagori8cicoia muri- Plates of fourth segment circular, 

 cata: a. Female, dorsal (drawn by projecting forward at each anterior 



J. H. Emerton, 1873) ; 6, male, • j i i i /^ -j. i 



^Qjgj^i corner m a rounded lobe. Genital 



segment strongly depressed; ab- 

 domen small and weak, attached to the ventral surface of the genital 

 segment, its posterior margin coinciding with that of the latter. 

 Caudal rami three times as long as wide, each with four apical setae 

 of about the same length. Total length, 10-15 mm. 



Retnarks. — In the female the teeth and spines on the carapace, and 

 the large size and toothed margins of the dorsal plates of the genital 

 segment, will serve to identify the species. In the male the dentate 

 margins of the dorsal plates on the fourth and genital segments are 

 characteristics. The dorsal surface of this parasite is often loaded 

 with algae, infusoria, hydrozoa, and even with the large-striped 

 barnacle {C onchoderma) ., which is as large as the copepod itself. 



Genus PHILORTHRAGORISCUS Horst, 1897 



Female. — Head fused with first segment; carapace orbicular, with 

 broad and rounded posterior lobes ; second and third segments fused, 

 with one pair of lateral plates, but no median ones ; dorsal plates of 

 fourth segment as wide as carapace, circular, almost entirely separated 

 by the median sinus, with a spine at each anterior corner and denticu- 

 late margins ; dorsal plates of genital segment nearly as large as cara- 

 pace, with denticulate margins. Abdomen 1-segmented, attached to 



