196 CEYLON PEARL OYSTER REPORT. 



T. caudatus, but the terminal claw is as short and weak as in the latter species. 

 No spine could be seen on its inner margin in any of the specimens examined 

 (fig. 25). 



The furca is small, the length four times the width, the branches short, simple, 

 divergent, and pointed, leaving a V-shaped sinus, only one-fourth or one-fifth the 

 entire length. 



The first swimming legs have a broad and well-rounded basal joint, carrying a 

 small seta on its posterior margin. Both rami are two-jointed, the exopod nearly 

 twice the length of the endopod. The basal joint of the exopod is considerably 

 wider than the terminal, and somewhat swollen ; the terminal joint is only half the 

 length of the basal, is not bent at a right angle as in T. caudatus, and is armed 

 with three short and stout spines on its distal end, and three plumose setae, as long 

 as the entire ramus, on its posterior margin. The basal joint of the endopod is also 

 twice the length of the terminal, and somewhat swollen ; the terminal joint is bent 

 at a right angle and tipped with three stout plumose setae. 



Second swimming legs similar to those of Lepeophthcirus in the shape and arrange- 

 ment of the joints and in the number and distribution of the spines and setae. 



The third swimming legs are like the second, bixt differ in a few particulars. The 

 exopod carries three spines on the outer margin of the terminal joint ; the basal 

 and second joints of the endopod are much enlarged, while the terminal joint is 

 reduced in size and carries only four plumose setae. 



The fourth swimming legs are very different from those of T. caudatus. The basal 

 joint is larger than that of the second legs, and almost circular. The exopod is 

 three-jointed and more than twice the length of the endopod ; the three joints are 

 about the same length, the two basal ones with a stout spine at the outer distal 

 corner, and a single plumose seta on the inner margin. The terminal joint has 

 three spines on its outer margin, the last one more than twice the length of the 

 other two, and four spines on the inner margin. The endopod has only two joints of 

 about the same size, the basal one carrying a single plumose seta on its inner margin, 

 the terminal one tipped with three such setae. 



The fifth legs are small and close to the lateral margin on the ventral surface of 

 the genital segment, a little in front of the posterior corners. 



The cement glands are comparatively wide and reach forward almost to the 

 anterior end of the segment ; their component cells are narrow and fill the entire 

 lumen of the glands. The sperm receptacle is a nearly straight tube of uniform 

 width, reaching across from one oviduct to the other. The spermatophores are 

 elongate-ellipsoidal, and are fastened close together on either side of the mid-line, 

 their long diameters parallel with the body axis (fig. 31). 



Total length 5 '75 milliius., length of carapace (including third thorax joint) 

 2 - 5 liiillinis.. width of same 2'1 millims.. length of genital segment 1*57 milliins., 

 length of abdomen l'l millims., length of egg-strings 3"! millims. 



