4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 6l 



The Cladocera and Ostracoda, too, were not numerous. The small 

 numbers of Cladocera presented a striking contrast to similar col- 

 lections made in the United States. 



DESCRIPTION OF THE COPEPODA 

 PSEUDODIAPTOMUS CULEBRENSIS, new species 



The cephalothorax is oval (pi. I, fig. i), the first segment being 

 about one-third its total length, and the first two together consider- 

 ably exceeding one-half the total length. The segments fit closely to- 

 gether with no overlap so that the dividing lines between the segments 

 are not very distinct on the lateral margins. The dorsal surface of the 

 fifth cephalothoracic segment is thickly beset with short hairs. The 

 angles of the last cephalothoracic segment are rounded and armed 

 with hairs. 



The first and second segments of the female abdomen (pi. I. fig. 2), 

 are about equal in length, and the third is about one-half the length 

 of the second. The furcal rami are long and slender and somewhat 

 less in length than the combined length of the second and third seg- 

 ments. There is a row of hairs on the left lateral margin of the 

 third segment and the inner margins of the furcse are ciliate. 



The abdomen of the male (pi. 1, fig. 4) is long and slender, all the 

 segments being of approximately the same width, and the three pre- 

 ceding the last, armed on the posterior border with a row of small 

 spines. The furcal rami are short, somewhat exceeding in length 

 the last abdominal segment, and ciliate on the inner margin. 



The antenna; are composed of 22 segments and somewhat exceed 

 in length the cephalothorax. The part of the male right antenna 

 beyond the geniculating joint (pi. I, fig. 7) is composed of two seg- 

 ments. The form of the swimming feet is typical of Pseudodiaptomus 

 (pi. 1, fig. 5). 



In the female fifth feet (pi. 1, fig. 3) the endopodites are wanting-. 

 The distal margin of the second basal segment is armed on one side 

 with a row of blunt spines and has a small lateral hair at almost one- 

 third its length. The exopodite consists of two segments and a hook 

 articulated to the second segment. Each segment of the exopodite 

 is armed at its outer distal angle with a long and slender spine. The 

 second segment has, in addition, on its inner distal margin, two spines, 

 one short, the other two-thirds as long as the spine on the outer margin 

 and ciliated. The terminal hook is slender and acute, about equal in 

 length to the first segment of the exopodite ; except for a sharp curve 

 at its base it is straight. It bears on the inner margin of the base a 

 short blunt spine. 





