NATURAL SCIENCES OF PHILADELPHIA. 309 



2. P. Foremani,* Lea. 



Melania Foremani, Lea, Philos. Proc, ii. p. 242. Philos, Trans., ix. p. 27. 

 Obs., iv. p. 27. Binney, Check List, No. 111. Brot. List, p. 30. 

 Reeve, Monog., f. 432. 

 Melania Foremanii, Lea, Wheatley, Cat. Shells, U. S., p. 25. 



3. P. undulatum, f Say. 



Melania undulata, Say, New Harmony Dissem., p. 261. Reprint, p. 17. 

 Binney's Edit., p. 142. Reeve, Monog., f. 307. Haldeman, Am. Jour. 

 Sci., xlii. p. 216, Dec, 1841. Anthony's List, 1st and 2d Edit. DeKay, 

 Moll. N. Y., p. 92. Wheatley, Cat. Shells U. S., p. 27. Jay, Cat., 

 4th Edit., p. 275. Binney, Check List, No. 281. Brot. List, p. 31. 

 Hanley, Conch. Misc.,t. 1, f. 10. Catlow, Conch. Nomenc. p. 189. 



Megara undulata, Say, Chenu, Man. Conchyl. i. f. 2025, 



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



Melania excurata, Conrad, New Fresh Water Shells, p. 49, t. 4, f. 6, 1834. 



Anthony, List, 1st and 2d Edit. Jay, Cat., 4th Edit., p. 273. DeKay, 



Moll. N. Y., p. 96. Binney, Check List, No. 103. 

 Melania excurvata,t Conrad, Wheatley, Cat. Shells U. S., p 25. 

 Melania rorata, Reeve, Monog. Mel., sp. 306. Brot. List., p. 31. 

 Io Spillmanii, 'Lea, Proc. Acad. Nat. Sci., p. 394, 1861. Jour. Acad. Nat. 



Sci., v. pt.'3, p. 348, t. 39, f. 215. Obs. ix. p. 170. 



5. P. m on il if e rum,|| Lea. 



Trypanosoma moniliferum, Lea, Proc. Acad. Nat. Sci., p. 172, 1862. Jour. 



Acad. Nat. Sci., v. pt. 3, p. 295, t. 36, f. 125, March, 1863. Obs., ix. 



p. 117. 

 Io nodosa, Lea, Proc. Acad. Sci. p. 393, 1861. Jour. Acad. Nat. Sci., v. pt. 



3, p. 346, t. 39, f. 212, March, 1863. Obs., ix. p. 168. 

 Io variabilis,^ Lea, Proc. Acad. Nat. Sci., p. 393, 1861. Jour. Acad. Nat. 



Sci., v. pt. 3, p. 347, t. 39, f. 214, March, 1863. Obs., ix. p. 169. 



6. P. nobile, Lea. 



Melania nobilis, Lea, Philos. Proc, iv. p. 165, Aug., 1845. Philos. Trans. 

 x. p. 65, t. 9, f. 48. Obs., iv. p. 65. Binney, Check List, No. 179. 



7. P. robus turn,** Lea. 



Io robusta, Lea, Proc. Acad. Nat. Sci., p. 393, 1861. Jour. Acad. Nat. Sci., 

 v. pt. 3, p. 346, t. 39, f. 213, March, 1863. Obs. ix. p. 168. 



B. Sulcate. ff 



8. P. canalic ula t urn, Say. 



Melania canaliculata, Say, Jour. Acad. Nat. Sci., ii. p. 175, January. 1821. 



* Prasinatum, Conrad ? 



f ~ Canaliculatum, Say? 



J Thetpyical excuratum differs widely enough from undulatum Say, but there exist intermedi- 

 ate forms of a nature to perplex the naturalist. Among these may be mentioned ponderosum, 

 Auth.,(dux, Lea) with the tubercles and canal nearly obsolete, and the revolving striae vevy feint, 

 so that the surface of the shell appears at first sight to be flat and smooth ; also annuliferum, Con., 

 in which the revolving lines are more strongly developed. These shells partake of one general 

 type, and form a natural group of closely related species at the least. 



\ Juvenile shell. 



|| Not so narrow in its proportions as excuratum, more frequently banded, and having the 

 upper whorls of the spire smooth, whereas in excuratum they are striate. This difference is more 

 apparent in comparing young specimens. 



\ Juvenile shell. 



** Not so much angled on the periphery as undulatum, with the inferior portion of the body 

 whorl longer and more convex. It bears the same general relation to undulatum as Trousti i dons 

 to canaliculatum; and the four may be but one species. 



ff The deep sulcus which distinguishes Mr. Say"s Melania canaliculata in its typical form, shades 

 off so gradually into a smooth flattened surface, that not only is it difficult to arrange the species 

 of this group, but it is even doubtful whether many of thespeues which are placed iu other groups 

 are really distinct. 



1863.] 



