NO. 1573. FA RASITIC COPEPODS— WILSON. 419 



relative size and shape of the four pairs of legs and their joints are 

 shown in Plate XXXII, figs. 177 to ISO, the magnification being the 

 same for each. 



Of the reproductive organs the (widucts are usually coiled once in 

 the genital segment, each strand of the coil reaching the entire length 

 of the segment. But sometimes there is a short extra coil in the 

 extreme anterior portion of the segment. The cement glands are 

 exceptionally large and broad and arranged like parenthesis marks 

 on either side of the intestine; the basal third of each is enlarged to 

 twice the width of the oviduct, is more or less rounded, and extends 

 outward and forward at an angle of 45° to the central axis. The re- 

 maining portion, or body of the gland, is once and a half the width of 

 the oviduct, curves around inward towanl the intestine, and extends 

 almost to the anterior border of the segment; the compound cells 

 are short and flattened like the eggs. The semen receptacle has the 

 shape of a spear or lance head, with a narrow tapering central sinus. 

 The two halves are joined anteriorly at the point of the spear, and 

 each has on its outer margin a rounded point or knob, corresponding 

 to the barb. 



Total length, 7 to 8 mm. ; length of carapace on mid-line, 2.75 nun. ; 

 width at posterior margin, 3.3 mm,; length of first dorsal plates, 1.5 

 mm.; of second pair, 0.75 mm.; of third pair, 1.25 mm.; of sixth 

 segment plate, 1 mm.; of abdomen, 2.25 mm. 



Color dull yellow or yellowish white, with a spot on either side 

 near the frontal margin of the carapace, or with the spots fused 

 across the mid-line into a horseshoe-shaped l)lotch opening ]>oste- 

 riorly. There is also a central irregular blotch on the third pair of 

 dorsal plates. In mature females the pigment of the eggs in the 

 coiled oviducts give the genital segment a grayish or brownish tinge. 

 From this mean the color varies in both directions. In specimens 

 from the Smooth Dogfish the brown or black markings often cover 

 most of the carapace, all of the fourth segment plates, and a part of 

 those oruthe second and third segments. On the other hand, speci- 

 mens taken from Atwood's Shark and immature specimens from 

 whatever source show no pigment at all, or only the faintest traces 

 of it. 



{sinuaius, sinuate, alluding to the posterior margin of the carapace.) 



Male. — Carapace orbicular, wider than long, with the lateral mar- 

 gin evenly rounded ; posterior lobes broadly triangular and curved 

 a little inward toward the mid-line; supplementary lobes very short, 

 at least three times as wide as long and close to the bases of the 

 posterior lobes. In preserved material these secondary lobes often 

 turn white or whitish and become opaque. Lateral grooves bent 

 sharply outward at the anterior ends, nearly at right angles to the 

 longitudinal axis, and terminating just behind the sucking disks. 



