STATE GEOLOGIST. 21 



ramus of the antennse has six setae on the basal, and ten or eleven 

 on the terminal joint, while the three-jointed ramus has a short 

 terminal joint bearing three spines. The valves are marked with 

 sparse spines on the lower margin. In most respects this species 

 is like Sida, which it resembles in size. In the form of the female 

 antennae it is like Latona which it also somewhat resembles in the 

 number of joints of the antennae and the numerous setae they bear. 

 It is certainly an interesting transition form. Found only in 

 swamps bordering Mobile bay, Ala., but whether in brackish or 

 fresh water my notes do not inform me. Sida crj^stallina lives far 

 out in the bay, and Daphnella is found in pools along shore. 



III. — Genus Limnosida. Sars. 



(Plate :N'. Fig. 9.) 



Head crested; eye in a conical prominence. Shell elongated, 

 produced above in an acute angle. Antennules small, truncate in 

 the female ; in the male of enormous size; antennae very long. 

 Post-abdomen smooth; terminal claw spiny. 



The one species, L. frontosa, Sars, is not yet known in America. 



lY. — Genus Daphnella. Baird. 



Neither beak nor fornices present. Antennules of female small, 

 truncate ; those of male long, flagellate. Antennse with two-and 

 three-jointed rami. Male with a hook on the first foot, and large 

 copulatory organs attached to the base of the post-abdomen. 



Sp. 1. Daphnella brachyura, Lievin. 



Sida brachyura, Lievin, Branch, d Danziger Geg. 



Daphnella wingii, Baird, Brit. Entom. 



Sida brachyura, Lii,i«teborg, De crust, ex ord. trib. 



Diaphanosoma brandtianum, Fischer. Erganzig. Berichtig. 



Daphnella brandtiana, Saks, Norges Ferskv. — Krebsdyr. 



Daphnella brachyura, P. E. Mueller, Danmark'sCladocera. 



Daphnella brachyura, Lutz, Untersuchung u. die Cladoceren d. Umg. v. Bern. 



Sida brachyura, Pavesti, Nuova serie di recerche della fauna pelagica nei laghi 



Itaiiani (L. Trasimene). 

 Daphnella brachyura, Herrick, Notes on Crustacea of Minnesota. 

 {Compare also D. expinosa, Birge, Notes on Cladocera p. 3.) 



The species of Daphnella found about Minneapolis, occasionally 

 abundant,, seems not to differ in any important character from 

 European types of D. brachyura, although I formerly regarded it 

 as distinct (D. winchelli. Microscopic Entom., Addenda). 



Head less than i the body (about .27 mm., while the body is 

 .6 mm. long); eye about i head; antennae when reflexed extend a 

 little beyond f the length of body. Male, .7 mm. long; antennae 



