COPEPOD GENUS HEMICYCLOPS — GOODING ] 77 



did not designate a typo nor mention where his specimens were 

 deposited. 



H. americanus was based (Wilson, 1932b) on a holotypc which, 

 together with one paratype, was deposited in the U.S. National 

 Museum. The vial of his specimens received from there contained 

 a "type" label (among others), which reads "Holotype Cat. No. 

 58563/To be selectcd/Paratype Cat. No. 63420," and two smaller 

 unlabeled vials, each with a single copepod. There is no indication 

 which of these Wilson intended to designate as the holotype, and 

 hence they are here considered syn types of americanus. 



Specimens examined: Wickford, Rhode Island, 1 female from 

 washings of intertidal rocks, G. M. Moore and N. W. Riser, June 

 13, 1057; this topotype was dissected and used for making all the 

 figures; the slide has been deposited in the U.S. National Museum, 

 USNM 101729. Chesapeake Bay, Maryland, 2 females from bottom 

 tow, U.S. Bureau of Fisheries, Station R' (off Cove Point), R. P. 

 Cowles, June 2, 1921, syn types of americanus (one was dissected). 



Redescmption of the female: Body very similar in appearance 

 to ihysanotus but genital segment not fused with first abdominal so 

 that urosome is 6-segmentcd. Length 1.58 mm. (mean of 3 speci- 

 mens, range 1.43-1.67 mm.); width of prosome 0.64 mm. (0.57-0.69 

 mm.). Genital segment roundish; genital openings median and 

 lateral. Ovisacs (one specimen) proportionately wider than those 

 of ihysanotus but only reaching distal border of second abdominal 

 segment. Lines of spinules on distal border of anal segment much 

 stronger than in ihysanotus and displaced outward. 



Caudal rami 2-2 K times as long as wide, with relatively long inner 

 dorsolateral seta and a tiny clement (which may represent a rudi- 

 mentary seta) near base on outer side. No setae modified as in 

 ihysanotus. 



Antennule like that of Ihysanotus except for setation on first 2 seg- 

 ments (5 on first, 14 on second); long setae on second, fourth, and 

 terminal segments relatively shorter and setae on second and fifth 

 segments apparently lacking cilia- 

 Antenna with fourth segment elongate and distal corner of third 

 hardly produced. Armature similar to ihysanotus condition but 

 spines on outer distal corner of third segment replaced b}^ setae and 

 these, together with that on first segment, with reduced ornamenta- 

 tion; isolated seta in terminal position bare. Curved setae with 

 region of irregular surface thickening reduced to short length near 

 position of greatest curvature and very thin flange often present 

 here; tips all with notch some distance from the end. No patch 

 of spinules on outer corner of second segment; third with 2 "comb 

 rows" on inner side; last with only a row of spinules. 



