﻿184 PROCEEDINGS OF THE NATIONAL MUSEUM vo 



Table 4. — Measurements of Megacyclops viridis (Jurine) from Erh Eai 



Measurement 



Total length, exclusive of caudal setae 



Furcal rami, length 



Furca, percent of total length 



Furca, Length: Width 



Inner corner caudal seta: 



Length.. 



Percent of totallength 



Inner terminal caudal seta: 



Length --. 



Percent of total length 



Outer terminal caudal seta; 



Length 



Percent of total length 



Outer corner caudal seta: 



Length 



Percent of total length 



Mean, with standard error ' 



2.48±0.071 mm 



243±4.556ai-- 



9.8±1.13 percent... 

 3.86±0.081.. 



509±6.965m 



20.64±2.92 percent 



H58±18.38|i 



46.78±7.73 percent 



872±21.61m 



35.24±5.73 percent 



239.3±0.39;i 



9.7±0.221 percent. 



Eange 



2.26-2.64 mm. 

 229-2fi0/i. 

 92-106 percent. 

 3.67-4.13. 



480-520M. 

 19.4-23.0 percent. 



1120-1232Ai. 

 44.6-49.1 percent. 



800-940M. 

 33.8-36.9 percent. 



237-240 M. 

 9.2-10.6 percent. 



1 Figures after ± indicate standard errors of the means. 



Order BRANCHIURA 



Family ARGULIDAE 0. F. Muller 



Genus ARGULUS O. F. Muller 



ARGULUS JAPONICUS Thiele 



Figures 25-30 



Among the plankton collected in one of the hauls made across 

 Lake Erh Hai, Yunnan, China, on November 28, 1945, was a large 

 number of argulids. In the course of determining their systematic 

 position it was found that the taxonomy of the species Arguliu japoni- 

 cus and A. trilineatus, which this plankton material resembles closely, 

 was in a confused condition. In the first place, descriptions of these 

 species by various authors differ widely, and the question of how 

 much should be accepted as variation within a species and whether 

 reclassification should be attempted needs to be worked out. In the 

 second place, the question of synonymy incolving A. japonicus and A. 

 trilineatus, the chief bone of contention between two American work- 

 ers, both examining specimens from the same collection at the National 

 Museum in "Washington, needs reexamination. It may serve some 

 useful purpose, particularly to students of copepods and fish culture, 

 to summarize in one place the more important points of the confused 

 situation in the literature as a part of this study of argulids from 

 Lake Erh Hai and to note the main characters of the specimens found 

 in this part of the world, so that future workers may use them for 

 comparison. 



Argulus japonicus was first described by Thiele (1900) from a single 

 female from Yeddo, Japan. His description consisted of a short note 



