COPEPODS OF THE WOODS HOLE REGION 489 



Color (preserved material). — Head, soft part of neck, and body 

 grayish yellow ; hard chitinous part of neck and egg strings orange- 

 yellow. 



FeTnale. — Head and neck in front of flexure soft, rest of body hard; 

 dorsal surface of head with central longitudinal ridge, two lateral 

 cushionlike processes projecting ventrally, and in front of them two 

 other cushionlike processes on the ventrolateral surface, also project- 

 ing ventrally. Second and third segments nearly as wide as head ; 

 fourth segment abruptly narrowed to half that width at the anterior 

 end, but widened posteriorly. First antenna 3-segmented; second 

 antenna 2-segmented, tipped with a chela; first maxillae apparently 

 lacking ; second maxillae 3-segmented, uncinate. First two pairs of 

 legs biramose, rami 2-segmented; third and fourth legs not found on 

 any specimen thus far examined. Total length, 30-40 mm. Diam- 

 eter of trunk, 4 mm. Egg strings, 125 mm. 



Re-marks. — This species can be identified by the sigmoid curve of 

 the body, the lateral processes of the head, and first two thoracic seg- 

 ments, and the spirally coiled Qgg strings. The sharp flexure of the 

 neck makes it very difficult to dissect the head and anterior thorax 

 out of the blood vessel in which they are immersed. In consequence 

 most investigators have never seen the parasite's head. 



Family PENNELLIDAE 

 Genus PENNELLA Oken, 1816 



Female. — Head fused with first segment and more or less globular, 

 usually somewhat flattened dorsoventrally, the anterior end trun- 

 cated and covered with short tumid processes, the posterior end 

 armed with two or three unbranched horns, usually chitinous. Neck 

 long, cylindrical, and passing insensibly into the trunk, which is 

 straight and transversely ridged. Abdomen long, distinctly annu- 

 lated, and tapered to a bil'obed tip, with a row of plumose appendages 

 along each side nearer the ventral surface, and a pair of minute 

 caudal rami with long setae. Egg strings filiform, several times the 

 length of the body. First antennae with few segments; second an- 

 tennae chelate ; mouth parts obsolete ; first two pairs of legs biramose, 

 close together; third and fourth pairs removed a short distance, 

 uniramose, all rami 2-segmented and setose. 



Gopepodid miale. — Head fused with first segment; second, third, 

 and fourth segments free and diminishing in width; fifth and geni- 

 tal segments fused; abdomen 1-segmented, caudal rami short and 

 wide and setose. First antennae indistinctly segmented; second an- 

 tennae 2-segmented with a stout chela ; mandibles, two pairs of max- 

 illae and a pair of maxillipeds present and well developed; swim- 

 ming legs like those of female ; no fifth legs. 



