ART. 18 SYNOPSIS OF CALANOID CRUSTACEA — MARSH 27 



larly arranged than in the corresponding spines of the left side. 

 The external spines of the second and third segments are elongated, 

 more or less sigmoid in form, and not armed with serrations or 

 denticulations. * 



In the fifth foot of the male (pi. 14, fig. 1) the second basipod of 

 the right foot bears a small spine near the external distal angle; 

 the exopod consists of two segments, the distal being rounded at the 

 tip. In the left fifth foot the process of the second basipod is long 

 and slender, gradually tajDering toward the distal end. 



Average length of female, 4 mm ; of male, 3.85 mm. 



Occurrence. — This species was first described from material col- 

 lected on St. Paul Island, Alaska. It has been found also in collec- 

 tions made by Dr. Frits Johansen on Herschel Island off the coast of 

 Yukon and in collections in tundra lakes made in the same general 

 neighborhood by J. M. Jessup. 



HETEROCOPE CASPIA Sars 



Heterocope caspia Sars, 1897, pp. 50-55, pi. 5, figs. 1-15. — Brehm, 1911, p. 487.— 

 Fadeew, 1926, p. 9, figs. 10-12.— Rylov, 1930. pp. 254-256, fig. 83, 1-7. 



In the female fifth foot the first basipods are not confluent, and 

 the last segment of the exopod does not bear a long spine, but resem- 

 bles the corresponding segment of the female fifth foot of Epischm^a. 



The exopod of the right fifth foot of the male is 1-segmented and 

 has a lobular external border. On the distal end of the terminal 

 segment of the left exopod are three small spines. The process of 

 the second basipod of the left foot is somewhat spatulate in form. 



The exopod of the second antenna has seven segments, the first, 

 third, fourth, fifth, and sixth being .short; this segmentation is like 

 that of Diaptomus rather than of typical Heterocope. 



Length : Female, less than 2 mm ; male, 1.5 mm. 



H. caspia differs quite materially from typical Heterocope. 



Occw^ence. — Found in the basin of the Caspian Sea in both fresh 

 and salt water. It is considered by some to belong to the fomna 

 relicta. 



Family PSEUDODIAPTOMIDAE 



Genus PSEUDODIAPTOMUS Herrick, 1884 



Pseudodiaptomus Herrick, 1884, pp. 180, 181. 

 Heterocalanus T. Scott, 1893, pp. 3^-41. 

 Weismanella Dahl, 1894, pp. 10, 11. 



No available synopsis of the species commonly assigned to the 

 genus Pseudodiaptomus has been made since 1898, when Giesbrecht 

 and Schmeil published " Copepoda, Gymnoplea " in Das Tierreich. 

 At that time there were nine recognized species. Now there are 24. 



