STATE GEOLOGIST. 23T 



The absence of teeth upon the .post-abdomen is of even generic im- 

 portance according to Sars, who gives it in his synopsi-' of genera as 

 typical for Daphnella. In our specimens the claws are at least pecti- 

 nate if not serrate, while the appendages of the male reach generally 

 nearly to the middle of the claws. The relative length of these ap- 

 pendages and the antennae of male is variable. 



Tribe II, a:n"omopoda. 



DAPHNID^. 



Rami of antennas 3 and 4-jointed; feet of five pairs; intestine with 

 anterior coeca not convolute. 



Genus MOii^A, Baird. 



A transition between Sididce and Dai^hnidtt is made through this 

 genus. 



Head separated from the body by a depression; macula nigra absent; 

 antennse of female large, movable, of male very long, curved; first 

 foot of male with strong hook; valves short, truncate behind. 



MOIKA BEACHIATA. 



We believe with P. E. Miiller that this and M. rectirostris are iden- 

 tical. The most complete discussion of the merits of the three species 

 (the above and M. paradoxa) is found in Weismann's paper, Ueber 

 einige neue oder unvollkotfunen gekannte Daphniden, Griiber and Weis- 

 mann, 1877, which see for bibliography and elaborate, not to say la- 

 bored, distinctions. This species is not common, but when found (in 

 muddy pools in late summer) frequently appears in great numbers. 

 For embryology see Grobben, Entwicklungsgeschichte der Moina 

 rectirostris. 



Genus daphnia. 



This genus as limited by Miiller is well distinguished from the re- 

 maining genera of the famiiy—S moce2)halus , Scapholeberis, Ceriodaphnia . 

 and Moina. 



As remarked by Birge, this is not the typical representative of the 



