﻿COPEPODS FROM LAKE ERH HAI, CHINA — HSIAO 189 



(1) The last (fourth) thoracic segment is without a constriction at 

 the center of each lateral margin. 



(2) Anal sinus is not V-shaped but depends upon how the caudal 

 lobes contracted and hardened during fixation, so its form is variable. 



(3) Second antenna is only 4- jointed, not 6- jointed, the fourth 

 (distal) joint being the shortest. 



(4) First and second swimming legs are with flagella. 



(5) Supporting ribs of the sucking cups are not made of nine pieces, 

 like a row of beads, but of six, the basal one longest in the form of a 

 rod, others platelike, diminishing in size distall3\ 



(6) Anal sinus though not half as long as abdomen, but almost one- 

 third rather than one-quarter as long. 



There were two possible explanations for this discrepancy. Either 

 Wilson made a mistake in his material or there are other specimens in 

 the National Museum collection that answer Wilson's description. 

 As it seems highly desirable to have all the specimens labeled A. 

 japonicus in the National Museum reexamined with the objective of 

 either invalidating Wilson's (1944) A. japonicus as a species if no 

 specimens agree with his description, or extending the range of varia- 

 tion of this universally occurring argulid, this problem was brought to 

 the notice of Dr. Fenner A. Chace, Jr., in the U. S. National Museum. 

 Dr. Chace, who had Paul L. Illg examine the types of A. triUneatus 

 and A. japonicus, made the following statement : 



The types of Argulus triUneatus are in two separate lots of one female each, 

 U. S. N. M. Nos. 32S28 and 39551. The former specimen is very flattened and 

 apparently has been dried out at some time. In the present condition the cara- 

 pace reaches to about the middle of the basal segment of the fourth legs, as seen 

 dorsally ; the specimen was too fragile to allow examination for flagella ; the 

 anterior dorsal ribs are forked. In a temporary mounting in Euparal, a count 

 of four segments to both second antennae was made under a compound micro- 

 scope ; the caudal rami were not determinable under a compound microscope. 

 A permanent Euparal mount of a fragment of the sucking disk was made and 

 six segments per supporting rib were made out, the innermost being the longest 

 and vaselike or rodlike. This is the Macon, Ga., specimen. 



In the other female, No. 39551, from Washington, D, C, the carapace reaches 

 to the fourth legs, which are completely visible in dorsal view; the dor.?al an- 

 terior ribs are forked; the first and second legs bear flagella. A permanent 

 mount of a portion of the sucking disk shows 6-segmented ribs. 



Of the allotype male, No. 78000, from Takoma Park, Md., five specimens remain 

 of the original six. In all, the carapace reaches to the fourth legs which 

 are entirely visible in dorsal view ; in all, the anterior dorsal ribs are forked. 



Of Argulus japonicus Thiele, there are but two lots from Tokio in the U. S. 

 National Museum, Nos. 78894 and 69835. The former contains a male and female 

 collected by A. S. Pearse and identified by Wilson. In both, the entire fourth 

 legs are visible dorsally ; the dorsal anterior ribs are forked ; the first and second 

 legs bear flagella ; the fourth segment is not laterally constricted ; the anal 

 sinus is plus or minus one-third the length of the abdomen ; the antennules and 



