THALESTRIS. 127 



4. THALESTRIS HARPACTOIDES, Glaus. PL L, figs. 9 16; 



and PL LIX, fig. 1. 



Thalestris harpactoides, Glaus. Die frei lebenden Copepoden, 

 p. 133, taf. xix, figs. 211 (1863). 



Body very slender and elongated, subsigraoid in 

 outline ; abdomen scarcely at all narrower than the 

 cephalothorax ; each segment bordered by a more or 

 less distinct belt ; rostrum of moderate size, slender ; 

 anterior antenna (fig. 9) 9-jointed, slender; inner 

 branch of lower antenna 2-jointed. Second foot-jaw 

 (fig. 12) slender ; hand elongated, ovate, much like 

 that of T. rufocincta, but the terminal claw is devoid of 

 basal setae, and is only 1 -jointed. Mouth organs and 

 first pair of feet also like those of rufocincta, but the 

 marginal seta3 of inner branch longer. The fifth pair 

 of feet in the female have a large, broadly triangular 

 basal joint (fig. 14) with ciliated inner margin, and five 

 setse of moderate length ; second joint broadly oval, 

 ciliated, obliquely truncate, and dentate distally, bear- 

 ing six setas, not much longer than the first joint ; 

 fifth feet of the male (fig. 1 5) almost exactly like those 

 of rufocincta. Abdominal segments (fig. 16) short 

 and wide, ciliated laterally, the first two scarcely 

 wider than the rest, and not produced into lateral 

 angles; posterior margins of the last two segments 

 finely dentate ; the second segment has also two spine- 

 like appendages (a a). Caudal segments about as long 

 as broad, armed with a small spine on the outer angle; 

 tail setae rather short, the inner one about as long as 



