8 PROCEEDINGS OF THE NATIONAL MUSEUM vol.82 



The cephalothorax is symmetrically oval (pi. 4, fig. 1), composed 

 of six segments, which decrease in length from before backward. 

 The first segment about equals the three following segments. The 

 last segment is bluntly rounded at the sides, and is not armed with 

 spines. 



The abdomen of the female (pi. 4, fig. 2) consists of four segments, 

 decreasing in length from the front backward. The furcal rami 

 about equal in length the third segment and are ciliate on the inner 

 border. The egg sacs are very large, extending nearly to the ends 

 of the furcal setae. The abdomen of the male (pi. 5, fig. 4) consists 

 of five segments, the fifth being short, hardly half as long as the 

 fourth. The furcal rami are ciliate. The furcal setae are long and 

 plumose, the fourth from the outside being the longest. The antennae 

 are 25-segmented and equal in length the cephalothorax or a little 

 more. The right antenna of the male (pi. 4, fig. 3) is geniculate 

 between the eighteenth and nineteenth segments. The antennae are 

 I'ichly supplied with sensory clubs. The segmentation of the second 

 antennae (pi. 5, fig. 5) is like that of Diaptoinus and Limnocalanus. 

 The mandible is shown in Plate 4, Figure 5. Swimming feet 1 to 5 

 are biramose and in all the endopods are 3-segmented. There is a 

 seta on the inner side of the first basal segment of all feet except 

 the fifth. 



The fifth feet of the female (pi. 5, fig. 1) are alike. The first basal 

 segment is armed on the outer margin with a very delicate hair. 

 The second segment is unarmed. The first and second segments of 

 the exopod have a stout spine at the outer distal angle; the inner 

 distal angle of the second segment is prolonged into a slightly curved 

 lamellate hook, which reaches the end of the third segment. The 

 third segment is armed with three spines and four setae; there is 

 also a short acute terminal spine. 



The first segment of the exopod is unarmed. The second segment 

 has a long seta at the inner distal angle; the third segment has a 

 lamellate spine on the outer margin and, on the inner margin and 

 the end, five setae. 



In the male the seta on the inner distal angle of the second seg- 

 ment of the exopod of the fourth "foot is peculiar in that the base 

 is much swollen, as shown in Plate 5, Figure 3, and the third segment 

 of the exopod is hollowed out on the inner proximal angle to re- 

 ceive the base of this seta. In Plate 5, Figure 2, is shown for com- 

 parison the female fourth foot, in which there is a slight indica- 

 tion of this enlargement of the seta of the second segment of the 

 exopod, but no modification of the inner proximal angle of the third 

 segment. 



