236 TENTH ANNUAL REPORT 



I note this cosmopolitan species, of which a nearly complete biblio- 

 graphy is given above, simply to mention that I have recently found 

 for the first time specimens of Sida reaching the size mentioned by 

 P. E. Miilier dVo cm.) 



In smaller pools, when present our Sida is much (often i) smaller, 

 and only in L. Minnetonka does the species attain its ultimate devel- 

 opment. 



Genus daphnella. 

 Superior ramus of second antennae apparently 2-iointed, narrow; 

 post-abdomen destitute of spines. 



DAPHNELLA BRACHYURA Licviu. 



(Plate VII, 11-16 ) 



Bibliography. 



Sida brachyura, Lieviii Branch, d Danziger Geg. 



Daphnella wingii, Baird, Brit. Entom 



Sida brachyura, Lilljeborg, De crust ex ord. trib. 



Diaphanosoma brandtianum, Fischer, Erganzig, Berichtig. 



Daphnella brandtiana, Sars, Norges Ferskv.— Krebsdyr. 



Daphnella br. hyura, P. E. MiiUer, Danmark's Cladocera. 



Daphnella brachyura, Lidz, Untersuchung li. die Cladoceren d. 



Umg. V. Bern. 



Sida brachyura, Pavesi, Nuova serie di recerche della fauna pelagica 



nei laghi italiani, (L. Trasimens.) 

 (Compare also /). 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 Euro- 

 pean types of 1). brachyura although I formerly regarded it as distinct 

 (Z). winchelli.) 



Head less than one-half the body (about ,JJo cm. while body is |o?)o 

 cm. long); eye about i head; antennae when reflexed extend a little 

 beyond I the length of body. Male , Jo cm. long; antennae reflexed 

 reaching base of shell; anterior antennae extremely long; copulating 

 organs reaching nearly to end of claws. Having carefully compared 

 our specimens with the description and figures given by Birge for his 

 D. expinosa, the evidence seems to indicate not only that they are 

 identical but both are really D. barchyura. The distinctive characters 

 of D, expinosa are a greater indentation between head and body, ab- 

 sence of caudal teeth, greater length of male appendages, and the 

 opening of the vasa deferentia in the *'instep" of these appendages. 



