NO. 6.] ACCOUNT OF THE SPECIES. 87 



inside with 4 well-developed natatory setae. At the tip, this joint carries a 

 slender spine, and outside 2 much smaller spines, which, like those of the 2 

 preceding joints, terminate in a thin flexible point. 



The 3 succeeding pairs (figs. 5, 6, 7) are essentially of the same structure, 

 though successively increasing somewhat in size. They have the inner ramus 

 scarcely more than half as long as the outer, and much narrower. Its last 

 joint in the 2nd and 3rd pairs carries 7, in the 4th pair 8 natatory setae, 

 2 of which issue from the outer edge. The outer ramu3 is distinguished hy 

 the large size and foliaceous character of the last joint, which, especially in 

 the 4th pair, is developed to quite an unusual extent, considerably exceeding 

 in size the 2 other joints combined. In all 3 pairs this joint carries 5 nata- 

 tory setae inside, 3 spines outside, and at the tip another somewhat larger 

 spine. Both the setae and the spines are unusually short. 



The 5th pair of legs (fig. 8) differ from the next preceding ones, not only 

 in their much smaller size, but also in some of the structural details. Thus 

 the 1st basal joint is without the plumose seta present in all the other pairs. 

 The inner ramus, as in the 1st pair, has only 8 natatory setae; but of these, 

 6 belong to the last joint, the 2nd joint having only a single seta. The 

 outer ramus is fully twice as long as the inner, and much stronger. In the 

 1st joint the natatory seta is wanting, and in the 2nd it is replaced by a 

 strong, incurved spine, finely denticulate in its outer part, and equalling in 

 length the last joint. The latter is about as long as the other 2 combined, 

 and carries 4 natatory seta? inside, 2 small spines outside, and at the tip a 

 much larger spine, as in the 3 preceding pairs, finely serrate outside. 



Occurrence. Solitary specimens of this form were found in 4 different 

 samples taken on the following dates: March 24th, 1894, between March 

 26th and April 4th, 1895, June 28th, 1895, November 12th, 1895. One of 

 these samples was taken from the very surface of the sea, the others in 

 depths of from 130 to 300 metres. 



Gen. Augaptilus, Giesbrecht. 



Remarks. This genus was established in the year 1892 by Dr. Gies- 

 brecht, to comprise 2 Mediterranean species formerly referred by Glaus to 

 the genus' Hemicalanus, viz H. filigerus and H. longicaudatus, and at the 

 same time he adds 5 new species from the tropical parts of the oceans, all 



