NO. 1573. PARASITIC COPEPODS— WILSON. 405 



the joints, and a single spine at the outer distal corner. The ter- 

 minal joint of the endopod of the second legs is three times as long 

 as the basal joint and slightly enlarged at the end; both joints without 

 spines. 



The exopod joints on these legs are the same length, but the ter- 

 minal one is much the wider and is armed \vith a row of eight or 

 nine large curved spines around its margin. The terminal endopod 

 joint of the third legs is two and a half times the length of the basal 

 joint and somewhat barrel-shaped, neither joint with spines. The 

 exopod joints are the same size, the terminal one with a cluster of 

 four or five spines at its tip. 



The rami of the fourth legs are broad and laminate, the exopod 

 twice the size of the endopod; the jointing is indistinct and the only 

 spines are on the exopod, one on the outer margin and a cluster of 

 three at the tip. 



Of the reproductive organs the semen receptacle is horseshoe- 

 shaped, the opening being posterior, and the two ends of the shoe 

 being enlarged into spheres; in preserved specimens it is usually 

 white and opaque. The cement glands can be seen on either side of 

 the intestine near the ventral surface of the genital segment. They 

 are shaped like parentheses marks, and in alcoholic material are dark 

 brown and opaque, with no traces of cells or divisions. The sperma- 

 tophores are large and are attached one on either side of the abdomen 

 at its base; the long thread-like ducts cross each other on the mid- 

 line and each empties the contents of its spermatophore into the geni- 

 tal opening on the opposite side of the body. The oviduct is usually 

 coiled once in each half of the genital segment, the last section pass- 

 ing down alongside of, and close to, the intestine and then turnina: 

 abruptly outward to the external opening (vulva) wdiich is in the 

 posterior lobe and just in front of the base of the anal laminae. 



Total length, 7.8 mm.; length of carapace on mid-line, 3.4 mm.; 

 width of same, 4.5 mm.; length of first thorax plates, 2 mm.; of 

 second pair, 1 mm.; of third pair, 1.2 mm.; of sixth segment plate, 

 1.6 mm.; of anal laminae, 1.8 mm.; of egg strings, 8.5 mm. 



Color, a light brownish yellow, more or less covered with dark 

 brown-black pigment; the amount of this pigment is very various, 

 but in the mature adult it usually covers the whole dorsal surface of 

 the thoracic plates except a narrow border around their margins, 

 and the whole center of the carapace, leaving a single large or two 

 separate small spots near the eyes, and the whole of the posterior 

 lobes free. 



Male. — General shape broad and flat, not strongly arched, with a 

 weak keel on the dorsal surface of the free and genital segments. 



Carapace a little wider than long, even including the posterior 

 lobes, one-half wider than long measured on the mid-line, trans- 



