NO. 6.] ACCOUNT OF THE SPECIES. 83 



The posterior antennae and oral parts are of exactly the same structure 

 as in the female. 



Of the legs, too, only the last pair (fig. 7) differ in structure from those 

 in the female. In both legs the outer ramus is transformed, and in the right 

 leg the basal part is also peculiarly modified, its 2nd joint sending out, inside, 

 a falciformly curved process, finely ciliated along the inner edge, and terminating 

 in a blunt point. The outer ramus of the right leg is somewhat larger than 

 that of the left, and otherwise also rather unlike it. Its 1st joint is conically 

 produced at the end outside, where it carries a short spine. The 2nd joint 

 has no spine, but forms, inside near the base, a rounded protuberance. The 

 last joint is fully as long as the other 2 combined, and is spoon-shaped, car- 

 rying 2 small lateral spines, and inside the tip a short bristle. The outer 

 ramus of the left leg is generally greatly incurved, and its 2 first joints 

 have each a well-marked spine at the end outside. The last joint is rounded 

 lamellar, with 2 rather strong lateral spines, and terminating in a slender 

 claw. None of these rami has any trace of natatory seta? inside. The inner 

 ramus is essentially of the same appearance in the two legs, being 3-articulate, 

 with the 1st joint very small and less perfectly defined. Each ramus carries 

 7 natatory setffi, one of which issues from the 2nd joint, the other 6 from 

 the last. 



Occurrence. This characteristic Calanoid occurred in the greater number 

 of the samples (13), and was found as frequently in the eastern as in the 

 western part of the basin traversed. It also occurred in the above-mentioned 

 sample, which was taken from the very surface of the sea. 



Distribution. Coast of Norway (only in depths below 100 fathoms); 

 the North Sea. 



18. Heterochceta compacta, n. sp. 

 (PI. XXIV, XXV). 



Specific Characters. 9- Body short and compact, with the anterior 

 division considerably tumefied and oval in form, rostral prominence much 

 smaller than in the preceding species, with the apical filaments shorter. 

 Tail scarcely more than Vs as long as the anterior division, genital segment 

 large and dilated, caudal rami somewhat less unequal than in H. norvegica. 



