310 [November, 



Dr. Leldy read a paper, intended for publication in the Proceedings, 

 entitleil " On some American Fresh-water Polyzoa." 



Also a second paper, intended for publication in the Journal, entitled 

 "Description of a new species of fossil Crocodile." 



Both communications were referred to the following Committee, Dr. 

 Ruschenberger, Dr. Fisher, and Dr. Le Conte. 



Mr. Lea read a letter from Mr. Edward Miller, giving the localities of 

 the coal fossils presented by him this evening. 



Mr. Lea also made some remarks on the scenery and geological cha- 

 racters of the White Mountains. 



The following resolution was unanimously adopted : 



Resolved, That the thanks of this Society be presented to Dr. E. K. 

 Kane, for the valuable donations made by him to the Museum of the 

 Academy, of specimens of Natural History collected during his recent 

 voyage to the Arctic Regions. 



November Ibth. 

 Vice President Bridges in the Chair. 



The Committee on Dr. Leidy's description of a new species of Fossil 

 Crocodile, from the Miocene of Virginia, reported in favor of publication 

 in the Journal. 



The Committee on the two following papers by Dr. Le Conte, reported 

 in favor of publication in the Proceedings. 



Synopsis of the specfes 0/ Donacia (Fabr.) inhabiting the United States. 

 By John L. Le Conte, M. D. 



*Elytri3 depressis, triangularibus, truncatis : oculis orbito praeditis. 



A. Crassiuscula), depressae ; antennae articuHs 2"*^" et 3'" subajfjualibus ; 

 elytra profunde striata; femora dente postice emarginato, vel crenato. 



1. D. mag n ifica, splendide violacea, aureo-marginata, thorace quadrate, 

 canaliculato, punctato, pedibus posticis magnis, tibiis incurvis. Long. '34. Lake 

 Superior. 



Mas, femoribus posticis bidentatis, tibiis intus serratis. Femina fern. post, uni- 

 dentatis, tibiis non serratis. Lee. 1,236. ID. dentata (Fabr.) Lac. 1,121. 



2. D. proxima, nigro-violacea, punctis inauratis, thorace quadrato, vix 

 punctulato, canaliculato, lateribus modice tuberculato, femoribus posticis magnis, 

 tibiis fere rectis. Long. -35 "43. Lake Superior, and Saratoga, (N. York.) 



Mas, tibiis posticis intus serratis, fern. post, tridentatis, dente anteriore parvo, 

 remoto. Femina, tibiis post, non serratis, fern, bidentatis, dentibus approximatis; 

 variat femoribus posticis unidentatis. 



Kirby. 225. D. episcopalis Lac. 1, 105. D. quadricolUs var. Say. J. Ac. 

 5, 282. 



B. Longiusculac, antennis attenuatis, articulo 3' 2"'^'' multo longiore, 

 thorace vis punctato. 



3. D. congener, aurea nitida, thorace quadrato, postice canaliculato, subti- 

 liter alutaceo, parceque punctulato, lateribus snbsinuatis,angulis non prominulis, 



