10 PROCEEDINGS OF THE ACADEMY OF 



perfect in all other particulars. A large plant running along a 

 rafter in his greenhouse, and producing hundreds of flowers, bore 

 these dimorphous ones in about equal proportions. He said it 

 was well known that in cultivation this plant never produced 

 fruit unless by artificial cross-impregnation, but he thought the 

 tendency to abort in the female flowers, and thus approach the 

 classes which were in structure as well as practically uni-sexual, 

 had not been noticed before. There was a species in New Zea- 

 land, however, known to be monoecious, and it might be just pos- 

 sible tiiat the Fassijloraceee, with mostl}^ hermaphrodite flowers, 

 were following in the wake of the allied Gucurbitacese, in which 

 a complete separation of the sexes was the rule. 



January 13. 



The President, Dr. Ruschenberger, in the chair. 



Twenty-six members present. 



Remarks on Hydi'a. Prof. Leidy remarked that two species 

 of Hydi^a were common in the neighborhood of Philadelphia. 

 One is of a light brownish hue and is found on the under side of 

 stones and on aquatic plants in the Delaware and Schuylkill rivers, 

 and in ditches communicating with the same. Preserved in an 

 aquarium, after some days the animals will often elongate the 

 tentacula for several inches in length. The green Hydra is found 

 in ponds and springs attached to aquatic plants. It has from six 

 to eight tentacles, which never elongate to the extent they do in 

 the brown Hydra. In winter the animal is frequently observed 

 with the male organs developed just below the head as a mamma- 

 like process on each side of the bod}'. He had not been able to 

 satisfy himself that these Hydrse were different from H. fusca and 

 H. viridis of Europe. Prof. Agassiz had indicated similar colored 

 forms in Massachusetts and Connecticut, under the names of H 

 carnea and H. gracilis. Of the former he remarks that it has 

 very short tentacles, and if this is correct under all circumstances, 

 it must be difterent from our brown Hydra, which can elongate its 

 arms for three inches or more. 



January 20. 



The President, Dr. Ruschenberger, in the chair. 

 Thirty members present. 



Prof. E. D. Cope described some species of extinct tortoises 

 from certain formations of Northeastern Colorado, which had 

 been previously found in the Fort Union or lignite beds of the 

 Missouri river region by Dr. Ha^^den. He had in 1868 recognized 



