248 



THE AMERICAN NATURALIST 



[Vol. XL 



segment of outer ramus about as long as second basal segment, over twice 

 as wide as long; second segment nearly twice as long as first, armed at 

 outer distal angle with a stout hook more than one half as long as the seg- 

 ment. Terminal hook stout, tapering, with a sharp curve at about the 

 middle, not quite as long as preceding segment, denticulate on inner mar- 

 gin beyond the sharp curve. 



Fifth feet of female (Fig. 9) with, the first basal segment bearing a very 

 large pointed process at the outer distal angle; second basal segment 

 armed with the usual marginal hair. Inner ramus one-segmented reach- 

 ing beyond the first segment of outer ramus, tips hairy and armed with 

 two plumose spines which are more than half as long as the ramus. Outer 

 ramus two-segmented ; first segment about twice as long as wide ; second 

 segment one third longer than first, curved, bluntly pointed, denticulate 

 on outer two thirds of inner margin and armed with three spines on the 

 outer margin of which the inner one (plumose) is longest and the outer 

 one shortest. 



Length: female, L47-1.58 mm.; male, L30-1.33 mm. 



This species somewhat resembles Diaptomus lintoni Forbes. 

 The specimens upon vi^hich the above description is based, were 

 collected in Wigwam Pond, Nantucket Island, Mass., May 30, 

 1905, by G. D. Richmond. There were three males and two 

 females. One of the latter was carrying eggs and both bore 

 spermatophores. 



Genus Cyclops O. F. Muller 



Cyclops leuckarti Claus. — Localities: Cambridge, Middlesex 

 Fells. 



Cyclops edax Forbes. — Localities: Cambridge, I^exington. 



Cyclops viridis insectus Forbes. — The most abundant member 

 of this genus in the collections examined. Localities: Arlington, 

 Cambridge, Brookline, Middlesex Fells, Nantucket, Waltham, 

 AYood's Hole. 



Cyclops viridis brevispinosus Herrick. — Localities: Cambridge, 

 \Vat(>rt()wii. 



Cyclops vernalis Fischer. — Localities: Brookline, Arlington. 



Cyclops bicuspidatus Claus. — This is a common species. Local- 

 ities: Arlington, Cambridge, Middlesex Fells, Nantucket, Wal- 

 tham. 



Cyclops fuscus (Jurine). — Localities: Brookline, Middlesex 

 Fells, Wellesley. 



