564 PROCEEDINGS OP THE NATIONAL MUSEUM. vol. 43. 



a very distinct keyhole-shaped space, the effect at this place being 

 like that of a cowlick (fig, 3 A) . 



The first antenna or antennule (fig. 2) is short and thick, equaling 

 or slightly exceeding the rostrum. The terminal olfactory setse are 

 delicate and equaling the antennule in length. The seta usual in 

 this genus on the posterior border has not been observed; neither is 

 the offset in which it usually stands present. Anteriorly, near the 

 end of the antennule is such an offset, but a seta was not observed. 

 Observations on this point are not conclusive, due, as shown later, 

 to the condition of the material. 



The second antenna, or antenna proper (fig. 4) , is with 7 swimming 

 setse, the usual seta upon the first segment of the inner ramus being re- 

 duced to a slender seta-like spine; the spines, therefore, 4, resembling 

 Acroperus. Setse ^ f f, spines ^ ^ ^. Spines, except as noted, quite 

 strong; setse segmented. 



The mandible is slender and curved. 



The maxilla (fig. 5) , as in CamptocerciLS and Acroperus, with 3 retrorse 

 teeth, the distal one smooth and nidimentary; the proximal two 

 ciliated, quite strong, and sub-equal in size. 



The feet are distinctly Lynceid in character. The first two pairs 

 (figs. 6 and 7) are hardly distinguishable from those of Alonopsis elon- 

 gata as figured by Dr. W. Lilljeborg.^ The third (fig. 8) and fourth 

 (figs. 9 and 10), however, resemble those of Camptocercus more closely 

 in the number of setse and the development of the ctenoid setse. The 

 fifth and sixth feet, if present, did not come under observation and 

 lack of material prevented adequate search for them. 



The postabdomen (fig. 11) is broad and strong, and is not long. The 

 dorsal or spine-bearing margin and the ventral margin are nearly par- 

 allel; the former broadly rounded at its end and not produced beyond 

 the claw-bearing extension of the latter. The distal half of the dorsal 

 margin, that is, beyond the anal opening is armed with a double row 

 of 11 small slender spines, slightly larger on the rounded end of 

 the postabdomen. There are no lateral denticles. The claw is upon 

 a fleshy base which has no spinules. The claw itself has a spine at 

 the base and at the middle of its concave border, and between them 

 fine spinules. The distal half of the claw is smooth. 



Male . — Unknown. 



Color is yellowish-golden. 



Occurrence. — The only specimens of this species are from the ali- 

 mentary tracts of fish by whom they were captured as food. The 

 condition of the specimens was not entirely satisfactory, especially 

 for internal structures. Specimens taken as follows: One specimen 

 from small-mouthed black bass, 31 mm. long, Sebago Lake, Maine, 



1 Cladocera Saeciae, Nova Acta Regiee Societatis Scientariiun Upsaliensls, vol. 19, pi. 65, figs. 11 and 12. 



