174 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



Most ventral seta on second segment of female maxilla replaced 

 here by a heavily sclerotised but unornamented hook which is con- 

 fluent with the segment. 



Maxilliped similar in basic plan to that of female but very different 

 in appearance. Only 1 seta on basal segment; 2 on second, which is 

 heart-shaped with several rows of spinules (the largest near base of 

 segment), much reduced in size and ornamentation and widely sepa- 

 rated. Terminal segment extended into a long, thick, curved process 

 bearing 3 setae as shown in the figure. (Longest of these setae is 

 very closely appressed to and often seems partially fused with basal 

 region of process ; this part may represent instead of a seta a partially 

 separated membrane. It is difficult to homoligize the armature of 

 this segment with that found in the female.) 



Only change in armature of swimming legs is loss of spine on inner 

 distal margin of first basipodite. 



First podomere of fifth legs completely fused with thoracic segment 

 but its seta and ornamentation remaining. Bases of this pair of legs 

 connected ventrally by a thickened strip. Strong cilia on inner edge 

 of terminal segment in female replaced by fewer spinules here and 

 these more distal in position. 



Sixth legs form paired flaps covering, in ventral view, most of 

 posterior half of genital segment ; a curved spine on each ventrolateral 

 corner. 



Remarks: My observations support neither the differences educed 

 by Wilson (1935) between H. callianassae and thysanotus nor the 

 characters stressed as diagnostic for pugettensis by Light and Hartman 

 (1937). Accordingly, the three species are here considered identical. 

 Since pugettensis is clearly a junior synonym, the valid name must 

 be selected from the other two. 



H. callianassae and thysanotus were described in the same publi- 

 cation (Wilson, 1935); the former, since it was listed first and de- 

 scribed in equal detail, would normally become the species name. 

 However, I propose to take advantage of "the principle of the first 

 reviser," reinstated in 1953 (International Commission on Zoological 

 Nomenclature, pp. 66-67), and examine the problem posed in this 

 instance by Giardella. 



As mentioned earlier (p. 160), the genus Giardella Canu, whose type 

 species (by monotypy) is 6. callianassae Canu, 1888, is very closely 

 related to Hemicyclops. In studying the literature, I have come to the 

 conclusion that it may eventually be desirable to expand the generic 

 concept of Hemicyclops so as to include this species. If page priority 

 is strictly applied in the case of Wilson's form, however, and callianas- 

 sae is chosen, any later merging of Giardella with Hemicyclops would 

 make it necessary to alter the name of his species. I believe that there 



