624 FrcsJi-Watcr ILntoinostraca. [October, 



in length. The superior antennae, usually very small or nearly ob- 

 solete in the Daphnoid.x-, arc the longer, but they agree with those 

 ofother members of the tribe in having little motion or play. 'rhe>e 

 many-jointed appendages constitute the trunk of our elephant, 

 lying as they do in so close ju.xtaposition as to seem a single or- 

 gan. The shell of l^rosmina is tuberculate and parti}', at leaNt. 

 reticulated with hexagonal cells. 



A group of smaller animals than any of the above is the old 

 family Lynccidcc which is now included in the Daphnid.Ti. Manx- 

 genera have been formed, but only one or two are founded ,on 

 reliable generic characters. Euryccrcus contains an animal nearly 

 as large as Daphnia, but the remaining animals are small and they 

 all agree in moving by a steady progressive motion rather than 

 by successive bounds, which peculiarity is due to the shortness of 

 the antennae. The head is sharper in front and a little black spot 

 beneath the eye, which is common to all Daphnjd?e becomes in 

 Lyuccus and its allies as conspicuous as the eye itself. This spot is 

 of unknown use but seertis connected with the base of tlie antenn;u. 



There are representatives of two genera of the family CypndiC 



to be found in every pool. ■ Tliese animals are enclosed in a shell 



^^hich covers not only the body but the head also, so that th' 



animal can withdraw entirely from view and close his shell about 



him like the mussel, which the shell much resembles in shape. 



The Cypris scurries about with an uncertain running motion, 



reminding one of the haste of an excited man,while the Candona 



loves the bottom. The inability to swim freely is due in Candona 



to the absence of the many setcC on the antennc-e (the principal 



motary org-ans), which broaden these paddles in Cypris. In this 



sketch only a very few forms have been glanced at, and the legion 



Phyllopoda containing BrancJiipus and the ** brine shrimp," has 



not been noticed, but objects enough to employ many a leisure 



day have been seen, any one of which might well repay weeks 



of study. 



DESCRIPTION OF PL.XTES.i 



Plate I. — Dinptonms lonf^icomis Hcrritk, back view of female and side view of 

 male; a, basal j)ortion of male anteiin.e showinj^ enlarj^ed sej,mients preceding gen- 

 iculating joint. 



Pl.ATK n. — Cyclops sp. ? a, last \r\\x of feet ; I, 2, 3, 4, 5, feet of Cyclops quadi i 

 cornis ; 6, inferic^r antennae. 



Plate \\\. — Sida oyslallina Straus, a, /', c, feet of first, second and last pairs ; d, 

 jaw : e, extremity of abdomen ; /, suj^erior antenna. 



Plate IV. — l, Hostnina lon;^irosfris ; a, portion of shell with superior antenn.v; 

 /', anterior antenna ; 2, Lynccus sji. ? 



1 Uicd through the kiiidncb- of J'n f. N. H Wiiichtll, Dircxtor of Miiuicsolu GoulugiL.il Survey. 



