THE MOUNT DESERT REGION" 217 



Rhynchotalona Norman 

 R. FALCATA (G. 0. Belts). (Birge, 1918, p. 724, fig. 1133.) 

 Uncommon. Station : S 23. 



Chydorus Leach 



C. FAviFORMis Birge. (Birge, 1918, p. 731, fig. 1148.) Found 

 rather rarely at S 23. 



C. BicoRNUTUs Doolittle. (Birge, 1918, p. 731, fig. 1149.) 

 Found with the preceding and in Witch Hole Pond. Also an 

 uncommon species. 



C. sPHAERicus 0. F. Miiller). (Birge, 1918, p. 732, fig. 

 1151.) Found abundantly in all ponds. Stations: S 22, 23, 

 Witch Hole. 



Suborder GYMNOMERA 



Tribe HAPLOPODA 



Polyphemidae 



Within this family Polyphemus, Podon, and Evadne form a 

 group which is quite distinct from Bythotrephes and its allies 

 from the Caspian Sea. The latter group seems to be un- 

 known in the Western Hemisphere. With one exception, all 

 the true marine Cladocera beyong to the present family and 

 the 2 species noted below are marine. Our forms breed in 

 July. 



Podon Lilljeborg 



P. LEucKARTii (G. 0. Sars). (Lilljeborg, 1901, p. 636, pi. 

 85, fig. 12; pL 86, figs. 1-3.) A common member of the 

 plankton. This is a northern species, and Sharpe's record 

 of it from Woods Hole is erroneous, applying probably to 

 P. intermedins. Stations : D 1, 54; P 5, 6, 10, 11. 



EvADNE Loven 

 E. NORDMAXNi Lovcu. (Lilljcborg, 1901, p. 641, pi. 86, figs. 

 4^17.) Found quite commonly with the preceding. Stations: 

 Dl, 30, 54;P5, 6, 10. 



