﻿COPEPODS FROM LAKE ERH HAI, CHINA — HSIAO 181 



with five somites. Sixth leg on posterior margin of genital somite 

 instead of being on the anterior half of this somite as in female 



(fig. 23, (7). 



This species is fairly abundant. Specimens collected in December 

 are all mature; the females are either carrying ovisacs or just through 

 with spawning, as evidenced by the remains of the outer shell of 

 the ovisacs. 



Types. — The type series consists of the female holotype and female 

 paratype, U.S.N.M. Nos. 84537 and 84538, respectively. 

 Subfamily Cyclopinae Kiefer 



Genus MEGACYCLOPS Kiefer 



MEGACYCLOPS VIRIDIS (Jurlne) 



Figure 24 



All the specimens found in Erh Hai in November are females. As 

 this species, the commonest cyclopoid found in all manner of waters, 

 is not euplanktonic but belongs to the littoral region, the specimens 

 in this collection might have been caught at the beginning and the 

 end as the plankton net was towed across the lake. All the females 

 were without eggs, but many had empty ovisac, or part of ovisac, still 

 attached to the side of the genital segment. There is a chance that 

 the females might have wandered offshore to spawn, or after spawn- 

 ing they went to open water. The males, on the other hand, stayed 

 among weeds near the margin of the lake and were not caught. 



Compared with specimens collected by Hutchinson in Kashmir and 

 Tibet (K 35 and L 16), the furcal rami seem to be longer in absolute 

 length, but their relative length in terms of total body length is not 

 significantly different. This is shown in columns 1 to 3 in table 3, 

 where the measurements from five individuals taken at random are 

 compared with the measurements made on five females by Kiefer 

 (1939). The wide range of variation of this percentage value — 92 to 

 106 for Yunnan material, 97 to 118.5 for Kashmir, and 78.5 to 104 for 

 Ladak — is, as pointed out by previous workers, due to the difference 

 in contraction of the preserved specimens. But this does not apply 

 to the measurement of the length and width of the furca which is a 

 single segment enclosed in a chitinous shell. In column 4 the ratio 

 between length and width is compared with Kiefer's observation on 

 Indian and Tibetan specimens. The Yunnan material seems to be 

 more like Tibetan (Ladak) than Indian. M. nmdis from Erh Hai 

 has longer inner and outer corner setae on the posterior end of the 

 furca. From columns 5 and 6 it will be seen that Kiefer's material 

 has inner corner seta 58 percent and outer corner seta 57-60 percent 

 as long as our specimens. But in both groups of animals the inner 



