160 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



genera Hersiliodes Canu (see Bocquet and Stock, 1957, for a dis- 

 cussion of the species currently included in this genus) and Giardella 

 Canu can be synonymized with He?nicyclops, I have not had a chance 

 to examine representatives of either. 



Thus, no definition of the genus is given here. All the species dis- 

 cussed share with the type species (H. yuvpureus Boeck, 1873, coast of 

 Norway) the lack of suckers on any of the appendages, a basic terminal 

 mandibular armature of four articulated processes, the presence 

 in the adult female of well-developed maxillipeds, and caudal 

 rami whose length does not exceed five times their width. H. thy- 

 sanotus, the first species treated here, since it was more intensively 

 studied, has been described somewhat more fully. Descriptions of j 

 the females of the other species are intended to be read with reference 

 to those preceding them; accounts of the males are, in addition, 

 supplementary to the descriptions of their respective females. It is 

 hoped that the illustrations, which represent in full the observations 

 I have been able to make, will alleviate any inconvenience this 

 arrangement may cause. A key to the American species is given 

 on p. 165. 



The terminology and abbreviations used are the same as those 

 of a previous paper (Gooding, 1957), except that "protopodite" I 

 replaces "basipodal segments" and "element" replaces "articulated 

 process"; "ornamentation" is restricted to "the complement of cilia 1 

 and/or spinules of a particular structure"; and "armature" denotes 

 "the complement of setae and/or spines of a particular structure."] 

 The last two definitions are, with permission, quoted from an un- 

 published thesis by Dr. Patricia Dudley. Terms such as "ventral," 

 "anterior," and "right," when used in describing appendages or their 

 parts, refer to these structures as they are oriented in the intact 

 animal: e.g., "inner side of maxilliped" is the side nearest the animal's 

 median longitudinal axis. For appendages which may change their 

 orientation, the most usual position has been chosen for the de- 

 scription. Alternative terms are given in the legends to the figures. 

 The phrase "burrow water" is used to refer to subsurface water ac- 

 cumulating in the hole created when digging for burrowing animals 

 (in this case, callianassids) . 



To facilitate reference in the text, collections and collecting areas 

 on the Pacific coast have been numbered thus: 



C.l: Elkhorn Slough, Monterey Bay, California, lat. 36° 49' N., long. 



123°16' W., from Callianassa californiensis Dana, G.E. Mac- 



Ginitie. For further details, see MacGinitie, 1935. 

 C.2: Tomales Bay, California, flats near Dillon Beach, lat. 38° 15' N., 



long. 122°58' W., from 18 Upogebia pugettensis (Dana), J. W. 



Hedgpeth, June 195G. 



