﻿COPEPODS FROM LAKE ERH HAI, CHINA — HSIAO 177 



It will also be seen from table 1 that with the exception of one 

 case (K 54) the difference between the lengths of the two terminal 

 spines is greater among North Indian and Tibetan specimens. The 

 specimens from Erh Hai show a ratio of 1.24-1.2'J only; among 

 Kiefer's material one spine may be one-third or one-half again as long 

 as the other. The spine formula of the last joint of the exopodites, 

 the corresponding seta formula, and the structure of the spines and 

 setae are the same as in E. s. serrulatus. But the details of the struc- 

 ture of the skeletal plates that join the third and fourth left legs with 

 those on the right side are different, as shown by figure 22, ^■, for the 

 fourth pair and figure 22, <9, for the third. When these figures are 

 compared with Kiefer's (1939) figure 14/ and our figure 22, n, the 

 difference will be apparent. As pointed out above, the hairs on these 

 plates of the subspecies E. serrulatus extensus from Erh Hai are much 

 longer and more irregularly arranged, instead of forming a single row 

 of short fine hairs on the posterior free edge. The setae of the fifth 

 pair of rudimentary legs are long as in specimens from Chushol, south 

 of Panggong Tso (L 72), not short like the Kashmir specimens from 

 Nishat Bagh (K 24) (cf. fig. 22, 6, with Kiefer's figs. 14^ and 14^). 

 The receptaculum seminis is of the common serrulatus type (fig. 22, e) . 



Adult male : Smaller than female, 0.815-0.900 mm. ; furcal rami not 

 so long as in the female, length-width ratio varies from (4.2 to 4.9) : 1, 

 outer edge without serration or lateral denticles. Sixth (or clasping) 

 foot with one spine and three setae, spine 42/i (range 39/x-44/x) , shorter 

 than second (or postgenital) segment, which measures 59/t-60/t. This 

 character distinguishes the males of this subspecies from those of E. s. 

 serrulatus. 



Five individuals from each sex of E. serrulatus extensus were taken 

 at random and their total length, excluding caudal setae, and the length 

 and width of the furcal rami were measured, and, in the case of the 

 males, the lengths of the innermost spine of the sixth foot were also 

 taken. In table 2 these data are arranged according to the size of 

 the animals. Kiefer found in North Indian and Tibetan specimens 

 that the length of the spine of the sixth foot ranges from ZSfi to 46/t 

 (he gave 40/<,-46/x but his table showed 38ju-46/u), with an average of 

 43fi. The average for Erh Hai specimens is 42/j, and the range 39|U,-44j«. 

 With the exception of one case, the length of the furcal rami seems 

 to increase with the increase in total length of the whole animal. 



Although the structure of the mandible of cyclopoids is used in the 

 classification of the group into families, no drawing of this organ in 

 the ser^rulatus group of species is included in the literature. In figure 

 22, /, it is shown for the first time for E. serrulatus. The reduced 

 mandibular palp carries three appendages, one very short and two 

 very long setae. The free ends of the long setae nearly reach the base 

 of the first swimming leg. 



852600—50 3 



