June, 1846.] 71 



A letter was read from H. Meigs, Esq., Secretary of the 

 local committee of the Association of American Geologists and 

 Naturalists, dated New York, June 5, 1846, transmitting a 

 number of printed circulars of that Association for distribution 

 among the members of the Academy. 



A letter from M. Alex. Moreau de Jonnes was read, accom- 

 panying his works presented this evening. 



Mr. Haldeman read a description of Unio abacoides, a new 

 species, which being intended for publication, was referred to a 

 committee consisting of Dr. Hallowell, Mr. Phillips and Mr. 

 Conrad. 



Mr. Fisher made some remarks on the comparative ra- 

 pidity of growth of plants at different periods of their exist- 

 ence. 



Dr. Leidy exhibited recent leaves of the common Elm, (Ulmus 

 fulva,) each having on the upper surface several large pyriform 

 excrescences, which were hollow and impervious, and contained 

 multitudes of Aphides in different stages of development, from 

 the larva to the perfect insect. 



Dr. Morton made some observations on the occasional union 

 or continuation of the spheno-temporal and coronal sutures in 

 the human subject. He finds it frequent in the Negro, occasional 

 in the Hindoo, Egyptian and aboriginal American, but has found 

 no instances of it in the European. He proposes to continue 

 his observations, and to present the precise results at a future 

 meeting of the Society. 



Dr. Morton also exhibited casts of some remarkable human 

 effigies, and other relics taken from Indian mounds in the vicinity 

 of Chilicothe, Ohio, by Dr. Davis and Mr. Squier, of that 

 city. 



Meeting for Business, June 80, 1846. 



Vice President Wetherill in the Chair. 



The Committee on Dr. Leidy's paper on the Anatomy of 

 Bradypus tridactylus, reported in favor of publication. 



