Philadelphia Jottrnal of Natural Sciences. 299 



genera of plants, Crypta and Hemianthus (of the natural or- 

 ders Portulacece and Lysimachi(e) ; and of two new plants, 

 Tillcea simplex, and Limosella tenuifolia. Description of CoU 

 linsia, a new genus belonging to the Antirrhinecie. 



Mr. Say has likewise some interesting papers relative 

 to the entomology, conchology, and crustaceology of North 

 America, of which we must content ourselves with only no- 

 ticing the heads. Description of several new land- and 

 fresh-water Shells. An Account of the Crustacea of the 

 United States. Description of several new Insects. An Ac- 

 count of the Hessian fly, Cecidomyia Destructor, of which an 

 interesting notice on its destructive ravages may be found in 

 Kirby and Spence's Entomology. Dr. Maclure has a paper 

 on the Geology of the West India Islands; and this part con- 

 cludes with an Account of the Incorporation, Library, Museum, 

 and Apparatus of the Society. 



Part II. We begin with the zoological papers of M. Le 

 Sueui', containing descriptions of several new fishes of the 

 Ameriam continent ; and of Machirite, a new genus of tur- 

 binated fossil shells. Mr. Say continues his account of the 

 Crustacea and Testacea of the United States, comprised in 

 several papers: — likewise a Description of three new Species 

 of Ncesa, a Genus of Crustacea, formed by Dr. Leach. Mr. 

 Ord has Observations on Grcectda Qiciscala and harita of the 

 Linnaean school ; and an Account of the Florida Jay of 

 Barton. From Dr. INIaclure, the president, there is an in- 

 teresting Essay on the Formation of Rocks, or an Inquiry into 

 the probable Origin of their present Form and Structure. 

 By Mr. Isaac Lee there is another valuable paper on the 

 Minerals at present known to exist in the vicinity of Phila- 

 delphia. The Botanical notices are few, and consist only of 

 Observations on the genus Glycine, and some of its kindred 

 genera, by Mr. Stephen Elliot. Description of several new 

 species of American Amphibia, by Mr. Professor Green ; and 

 of two new species of Linnaean hacerta, by Mr. Jacob Gil- 

 liams. Description of three new Fishes, by Dr. T. Mitchill, 

 also of three new genera of Fishes, by Professor Rafinesque. 

 The miscellaneous papers are : Description of a Hydrostatic 

 Balance, by which the specific gravity of minerals may be as- 

 certained without calculation, by Dr. Coates. A Case of an 

 unusual Arrangement in the ascending Cava and in the ex- 

 ternal Jugular veins of the Human Subject, by Dr. Horner. 

 The usual lists of the library, museum, donations, &c. are at 

 the end of the volume. 



In the three succeeding numbers of this work, being all 



that have yet reached us, are contained the following papers : 



P p 2 Account 



