NO. 1573. PARASITIC COPEPODS— WILSON. 469 



When the female is without egg-strings, the lateral and anterior mar- 

 gins of these laminae are turned upward into scrolls, similar to those 

 formed by the dorsal plates of the genital segment, and inside of them. 

 The lateral margin is also caught inward in a large fold on either side 

 about one-fourth the distance from its anterior end. This gives the 

 ventral aspect of the abdomen a peculiar T shape, the upright portion 

 being more than twice the width of the arms. When the egg-strings 

 are extruded, these folds and the scrolls along the lateral margins. are 

 straightened out and each lamina rests flatly upon the ventral surface 

 of the coiled egg-strings, completely concealing them in ventral view 

 (fig. 254) . The scrolls along the anterior margin are never entirely 

 straightened, but the lamina on either side curls up over the eggs at 

 that point and holds them securely in place. The anal laminae are 

 small, orbicular, and attached close to the anus on either side; they 

 are armed with short and stout spines and have no plumose setiie. 



The first antennae are two-jointed, the basal joint much the longer, 

 each joint armed with a few short spines. Second })air large and 

 powerfid, the principal organs of prehension, three-jointed, the ter- 

 minal joint a strong sickle-shaped claw, which is buried in the flesh 

 of the host. The terminal joint of the fu-st maxillipeds is nmch 

 shorter and more slender than the basal; the terminal claw is nearly 

 as long as the joint itself and only slightly curved; the accessory 

 claw is much shorter, while both claws have serrate edges. The 

 second maxillipeds are stout, but not swollen, as in the Pandarince, 

 the curved terminal claw nearly as long as the basal joint and shut- 

 ting down between two large corrugated laiobs on the ventral sur- 

 face of the latter. 



Mouth tube and maxillae peculiar, the former conical with a wide 

 and swollen base, tapering rapidly to a fairly sharp tip, from which 

 protrude the ends of the mandibles. These latter are straight and 

 coarsely toothed along their inner margins, the teetli being more or 

 less rectangular. Maxilla^ enormous and clul)-shaped, each one as 

 large as the whole mouth tube and two-jointed, its hemispherical 

 terminal joint covered with small curved spines. On the ventral 

 surface of each maxilla, at the base of the terminal joint, is a small 

 knob representing the rudiments of the exopod. 



Swimming legs biramose, rami two-jointed, except those of the 

 fourth pair, which are modified into large laminae with indistinguish- 

 able joints. The basal joints of the exopods of the first two pairs 

 are much larger than the terminal joints and are armed with a stout 

 spine at their outer distal corners, the one on the second legs being 

 exceptionally large. The segments of the third legs are all the same 

 size, while in the fourth legs the rudimentary endopod is several 

 times larger than the exopod. In these latter legs there is also a 

 large fold of skin caught up on the ventral surface of each basal joint. 



