COPEPODS OP THE WOODS HOLE REGION 443 



Male. — Carapace and second and third segments similar to those 

 of the female; dorsal plates of the fourth segment only half the 

 width of the carapace and covering the whole of the genital segment 

 and abdomen, except the caudal rami; combined they are one-half 

 wider than long. Genital segment nearly twice as wide as long, much 

 narrowed where it joins the fourth segment, and without dorsal 

 plates. Abdomen half as wide, but much less than half as long, 

 as the genital segment ; caudal rami small, with small plumose setae. 

 Total length, 14-17 mm. 



Remarks. — This is one of the largest copepods, and in the present 

 area it has been thus far confined to the sunfish for a host, but else- 

 where it has been found upon several other kinds of fish. 



Genus ORTHAGORISCICOLA Poche, 1902 



Fetnale. — Head fused with first segment, carapace wider than long, 

 narrowed anteriorly, its lateral margins coarsely toothed, its dorsal 

 surface sparsely covered with spines. Second and third segments 

 distinct, with only rudiments of dorsal plates; fourth segment with 

 dorsal plates covering half the genital segment, their margins ser- 

 rate. Dorsal plates of genital segment much wider and longer than 

 the carapace, overlapping each other on the midline, with serrate 

 posterior margins. Abdomen concealed, with lateral lobes as in 

 Gecroys; egg strings carried between these lobes and the dorsal plates. 

 Rami of first two pairs of legs 2-segmented, of third and fourth pairs 

 large 1-segmented laminae, without setae. 



Male. — Carapace similar to that of female, but the margins are 

 not toothed, and the dorsal surface has no spines; second and third 

 segments forming a narrow waist, without dorsal plates ; fourth seg- 

 ment plates a little narrower than the carapace, covering more than 

 half the genital segment, their posterior margins serrate. Genital 

 segment only two-thirds the size of the carapace, its dorsal plates 

 narrower than those of the fourth segment, and serrate posteriorly. 

 Abdomen small, quadrangular, showing through the posterior sinus 

 of the genital segment plates. Rami of first three pairs of legs 

 2-segmented, of fourth pair 1-segmented, much enlarged laminae, 

 armed only with spinules. 



ORTHAGORISCICOLA MURICATA (Kr^yer) 

 FiGUBB 279 



Laemargus muricatus Kr0teie, Naturh. Tidsskrift, vol. 1, p. 487, pi. 5, figs. A-E, 



1837. 

 Orthagoriscicola muricata Wilson, Proc. U. S. Nat. Mus., vol. 33, p. 473, pis. 40, 



41, 1907. 



Occurrence. — Found on the gills of the common sunfish and of the 

 lookdown {Selene vomer) captured near Woods Hole. 



