COPEPODS OF THE WOODS HOLE EEGION 493 



legs are more often lacking in the female, but one or two pairs are 

 usually present in the male. In several genera all segmented append- 

 ages are obsolete, and in one or two there is also no distinction of 

 body regions. 



Two ovisacs, club shaped, spherical, or cylindrical; eggs multise- 

 riate and pressed so tightly together that they are flattened into 

 polygons; nauplius and often metanauplius stages passed within the 

 egg, the larva emerging in the first copepodid stage and attaching 

 itself at once to its host by means of a frontal filament. The female 

 becomes a fixed parasite attached immovably to its host, the male 

 clings to the female and can crawl about more or less over her body. 



Remarks. — ^Although the male is a pygmy and is usually identified 

 by the female to which it is attached, it does furnish useful generic 

 characters and for this reason the males appear in the key (Appendix 

 B, p. 538) as well as the females. Every genus in the group is a 

 fixed parasite and all kinds of modification, transformation, and 

 degeneration are exhibited among them. The ultimate limit is 

 apparently reached in the genus Xenocoeloma where nothing is left 

 in the adult except the posterior portion of the digestive tract and two 

 ovisacs, and the copepod has become hermaphroditic. 



Family CHONDRACANTHIDAE 

 Genus BLIAS Kr0yer, 1863 



FeTThdle. — Head separated from the trunk by a groove, which 

 extends entirely around the body; remainder of thorax and genital 

 segment fused into a smooth trunk without appendages or processes ; 

 abdomen separate, much reduced in size, 2-segmented, with caudal 

 rami. First antennae with few segments; second antennae pre- 

 hensile ; mouth parts near posterior margin of head and made up of 

 mandibles and two pairs of maxillae; swimming legs lacking. 



Male. — A pygmy attached to the female by its second antennae; 

 body pyriform, distinctly segmented, with two pairs of antennae, 4 

 pairs of mouth parts, and two pairs of rudimentary legs. A single 

 species in the present area. 



BLIAS PRIONOTI Kr0yer 



FiGtJEB 296, a, 

 Blias prionoti Kr0yer, Naturh. Tidsskrift, ser. 3, vol. 2, p. 262, pi. 12, fig. 5, 1863. 



Occurrence. — Two females were taken from the gills of a sea robin 

 (Prionofus) at Woods Hole, June, 1904. 



Distribution. — Coast of Brazil (Kr0yer). 



Color. — This copepod has never been seen alive; preserved speci- 

 mens are a uniform yellowish brown. 

 71937—32 33 



