PARASITIC COPEPODS — WILSON 575 



may safely be regarded as the two sexes of paulensis. Thus we have 

 three males just alike and one of them is proved to be the male of 

 paidensis through association with two females. The only sensible 

 disposal of the other two, considering the fact that they do not agree 

 with the type male of salmi?iei, is to transfer them to the species 

 paulensis, with the male of which they do agree, and to conclude that 

 Thiele was mistaken in his identification. 



NOTE ON THE KEY TO THE SPECIES OF ARGULUS 



The key to the species of Argulus published in Meehean's paper 

 (1940, pp. 475-479) is here used as a basis for a new key. The key is 

 based on only the species of which material for examination was avail- 

 able in the collections of the United States National Museum {cf. p. 

 552, footnote 8, and p. 576, footnote 11) . In it are included eight species 

 that Meehean regarded as synonyms, four new species, and one new 

 name. Using the characters for identification that appear in the key, 

 the eight species that Meehean took to be synonyms are found to have 

 validity as creditable as any of the species included. 



Meehean's key has real worth and is of great value in determining 

 the species of Argulus. However, it placed excessive value upon the 

 respiratory areas and the supporting ribs of the suction cups. The 

 insertion of the eight species shows how easily the real validity can be 

 established by carrying the analysis to further details without im- 

 pairing the testimony of the areas and ribs. A key that will allow 

 this may be depended upon for the reception of new species that may 

 appear in the future. 



In distinguishing A. hicolor from A. fuscus in the original key 

 hicolor shows as much widening in the posterior portion of the larger 

 respiratory areas as is seen in fuscus. Dr. Bere shows no widening in 

 the latter species. 



The species A. salminei Meehean has been shown to combine both 

 A. nattereri and A. paulensis, which are valid species, and as sufficient 

 structural details of Kr0yer's salminei are not available for want of 

 actual specimens this species has not been included in this key. 



A new name, diversus, is given to Meehean's nrvaculosus, which was 

 preoccupied. 



A. hiramosu^ Bere (p. 568) is not included in the key. No male has 

 been discovered and without males the species cannot be fully charac- 

 terized. It may be questioned that this species is identical with 

 appendiculosus, as Meehean believes. In the type specimen of ap- 

 p€7idicuIostis the dorsal ribs of the carapace were not branched 

 anteriorly. 



An asterisk following a specific name indicates that this actual 

 species did not appear in the original key published by Meehean. 



