26 PEOCEEDINGS OF THE ACADEMY OF [Jan., 



no hyaline plates and the last three gradually increase in length to 

 the end. 



The armature of the swimming feet is as follows : 



First pair — outer ramus, two spines, four setse; inner ramus, one 



seta, one spine, four setse. 

 Second pair — outer ramus, three spines, four setae; inner ramus, one 



seta, one spine, four setse. 

 Third pair — like second. 

 Fourth pair — outer ramus, three spines, four setse; inner ramus, one 



seta, two spines, two setse. 



The fifth foot (PI. II, fig. 4) is two-segmented, the basal segment 

 being about as long as broad and bearing a plumose seta on its outer 

 distal angle. The distal segment is cylindrical, about twice as long 

 as Avide, and bears a long plumose seta and a short, thick spine. 

 For this spine is often substituted a longer seta-like form, though 

 that is not the regular armature in the local specimens. 



The receptacuhim seminis (PI. II, fig. 5) consists of two divisions. 

 The anterior portion extends as a low arch across the segment. The 

 posterior division is bag-shaped and reaches a point half-way to the 

 posterior margin of the first abdominal segment. Its anterior border 

 branches out abruptly on either side along the suture. The porus 

 is situated on the median line, between the lateral angles on the 

 suture. 



The egg-sacs are unusually large and are carried at a considerable 

 angle from the body. Forbes gives the size of this species as 1-1.4 

 mm. Schmeil gives 1.3-2 mm. for the European forms. The 

 specimens from this locality average about 1.5 mm. 



The color of C. bicuspidatus is generally a very pale shade of 

 yellow. Often individuals appear to be quite colorless. The dorsal 

 surface of the thorax, especially the anterior portion, usually has a 

 peculiarly shiny appearance. 



The last characters for the distinction of this species are its slim 

 form, the shape of the fifth feet and the receptacuhim seminis, and 

 especially the. small lateral combs of spinules on the outer sides of 

 the stylets. 



Subgenus MARCOCYCLOPS Claus. 

 Cyclops fuSCUS Jurinc. PI. I. 



Mottoculus quadricnrnis fii.scus Jurine, '20, pp. 47, 48, Taf. II, fig. 2. 

 Cyclops signnlu.^ Koch, '3S, Ileft, 21, Nr. 8. 



Cyclops conmalus Clans, '()3, i)p. 97-99, Taf. II, fig. 16 and Taf. X, fig. 1. 

 Cyclops signalus var. coronalus Herrick and Turner, '95, p. 106, pi. XV, 

 figs. 1-4. 



