NATURAL SCIENCES OF PHILADELPHIA. 19 



Synonymy of the Species of STREPOMATIDJE, a Family of Fluviatile Mollusca 



inhabiting North America. 



Part 4. 



BY GEORGE W. TRYON, JR. 



The first, second and third parts of this paper* included all the species then 

 known to science, except a peculiar group, of about sixty species of Gonio- 

 basis, inhabiting principally the Coosa River, Alabama. The species of this 

 group are distinguished from others of the genus by their heavy, bulbous or 

 cylindrical, or pupseform shapes, and their very short spires. I was not sat- 

 isfied that they belonged to the genus Goniobasis, and therefore reserved them 

 for further study. 



Mr. Lea has since eliminated from this group principally, his excellent ge- 

 nus Euryccelon, which still leaves most of the species, however, in Goniobasis. 

 Finding that I am still unable to make a satisfactory separation, I have con- 

 cluded to finish the synonymy, treating these shells as Goniobases. 



I avail myself of this opportunity to publish those additions and corrections 

 in the synonymy of the first three parts, which the kind assistance of my 

 friends, and particularly of Mr. Lea, together with my own investigations 

 have enabled me to make. 



Including the species of the present paper, my Catalogue now embraces 

 about five hundred species and three hundred synonymsf. 



10, Lea. 

 1. I. f 1 u viali s, Say. 

 Iojluviatilis, H. and A. Adams' Genera i. p. 299. Brot, Malaco Blatt. ii. p. 



114, July, 1860. 

 Io fusiformis, Lea, Chenu, Man. Conchyl. i. f. 1977. 

 Io fusiformis, Say, H. and A. Adams' Genera i. p. 299. 

 Jo tenebrosa, Lea, H. and A. Adams' Genera i. p. 299. Troschel, Archiv fur 

 Naturgesch. ii. p. 130, 1843. 



3. 1. s p i n o s a, Lea. 



Io spinosa, Lea, Chenu, Man. de Conchyl. i. f. 1973. Morcli, Yoldi, Cat. p. 

 56. Adams' Genera i. p. 299. 



PLEUROCERA, Raf. 



1. P. alveare, Con. 



Melania alveare, Conr., Midler, Synopsis, p. 46, 1836. 

 Megara alveare, Con., Adams' Genera i. p. 306. 

 Megara torquata, Lea, Adams' Genera i. p. 306. 

 Io pernodosa, Lea, Adams' Genera i. p. 299. 



2. P. Foreman i, Lea. 



Gyrotoma Foremani, Lea, ? Adams' Genera i. p. 305. 



3. P. undulatum, Say. 



Melania undulata, Say, Brot, Mai. Blatt. ii. p. 106, July, 1860. 

 Megara undulata, Say, Adams' Genera i. p. 306. 



4. P. e x c u r a t u m, Conrad. 



Melania excurata, Conr., Midler, Synopsis, p. 43, 1836. 



Proceedings Acad. Nat. Sciences, Nov., 1863, p. 306; Feb., 1864, p. 24; April, 1864, p. 92. 

 t The species, published by Mr. Lea in the Proceedings of the Academy for 1864, are not all in- 

 cluded in this paper, as the short diagnoses do not allow me to place them in a satisfactory manner. 

 As soon as the full descriptions and figures ate published in our Journal. I will indicate their 

 proper places in this list 



1865.] 



