NO. 1589. FRESH-WATER CRUSTACEA— CUSHMAN. 707 



Order CLADOCERA. 



Family DAPHNID.^. 



Genus DAPHNIA O. F. MUller, 178S. 



DAPHNIA PULEX (DeGeer.) 



Plate LIX, figs. 1-3. 



Monociilus ptilex De Geer, Memoires pour servir a Tliistoire natiu-elle des 



Inseetes, VII, 1778, p. 442, pi. xxvii, figs. 1-8. 

 Daphnia pulex Baird, British Entomostraca, 1850, p. 89, pi. vi, figs. 1-3; 



pi. IX, fig. 5. — LiLLJEBORG, Cladocera Suecise, Nova Acta Reg. Soc. Sc. 



Upsala, 3cl ser., XIX, 1900, p. 79, pi. ix, fig. 8 ; pi. x, figs. 1-9 ; pi. xi, 



figs. 1-11 ; pi. XII, figs. 1-13. 



Length of female about 3.5 mm. 



The outline of the females of this and other species varies according 

 to the condition of the ephippium. A typical outline is shown in 

 Plate LIX, fig. 1. The shell sculpture consists of two sets of straight 

 lines at an oblique angle, forming a network with four-sided meshes. 

 The outline of the head, (Plate LIX, fig 2,) has the rostrum more or 

 less acuminate, by which it diifers from its close ally, D. atkmsoni 

 Baird. The basal line of the post-abdomen is nearly straight, thus 

 easily separated from D. 7nagna Strauss, which is very sinuate in 

 outline. From the two common species, D. hyalina Leydig and D. 

 longispina^ O. F. Miiller, it may be distinguished by the spines at the 

 base of the f ureal claws. (Plate LIX, fig. 3.) 



This species was common in the material from Labrador, being 

 found in four of the five lots of material. St. Marys River, July 12, 

 1906, common. Great Caribou Island, July 14, 1906, few. Battle 

 Harbor, July 14, 1906, few. At this last place a little later in the 

 season, August 1, 1906, the species was abundant and the young in 

 all stages of development were found. No males were found in any 

 of the material. This species is widely distributed both in the Old 

 World and in America. 



Genus SIMOCEPHALUS E. Schoedler, 18S8. 



SIMOCEPHALUS SERRULATUS (Koch). 



Plate LIX, figs. 4, 5. 



Daphnia scrrulata Koch, Deutsclilands Criistaceen, Myriapotlen uud Arch- 



niden, 1841, Heft 35, pi. xiv. 

 Simocephulits serrtilatus E. Schoedler, Die Branchipodeu der Umgegend 



von Berlin, Jahresbericht iiber die Louiseustadtische Realsclinle, 



Berlin, 1858, p. 22. — liiLLJEBORG, Cladocera Sueci», Nova Acta Reg. 



Soc. Sc. Upsala, 3d ser., XIX, 1900, p. 179, pi. xxvi, figs. 9-16. 



Length of females about 2.5 mm. 



As in Daphnia, this species varies greatly in outline. In the speci- 

 men of which an outline is given (Plate LIX, fig. 4), there were sev- 

 eral eggs in the ephippial sac, causing a distention of the body at the 



