61 



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

 inhabiting North America. 



Part 3. 

 BY GEORGE W. TRYON, JR. 



Genus SCHIZOSTOMA, Lea. 



Schizostoma, Lea, Philos. Proc. ii. p. 242, Dec. 1842, iv. p. 167, Aug. 1845. 



Philos. Trans, x. p. 67, 1847. Obs. iv. p. 41, 1847. Proc. Acad. Nat. 



Sci., May, 1860. Jour. Acad. Nat. Sci. v. pt. 3, p. 245, Mar., 1863. Obs. 



ix. p. 67. 



Schizocheilus, Lea, Philos. Trans, x. p. 295, 1853. Obs. v. p. 51, 1853. 

 Gyrotoma, Shuttleworth, Mittheil, Naturforsch. Bern. p. 88, July 22, 1845. 



Adams, Genera, i. p. 305, Feb., 1854. Gray, Guide to Mollusca, i. p. 103, 



1857. Chenu, Man. de Conchyl. i. p. 293, 1859. Anthony, Proc. Acad. 



Nat. Sci., p. 63, Feb., 1860. Binney, Check List, June, 1860. Brot, 



List, p. 27, 1862. 

 Melatoma, Anthony, Gray, Zool. Proc., p. 153, 1847. Woodward, Manual, p. 



131, 1851, Reeve, Conch. Icon., Mar., 1860. 

 Avella, Mighels, MSS. 



SYNOPTICAL TABLE OF SPECIES.* 



Fissure direct, narrow, and deep. Fissure oblique, short, and wide. 



1. Shell striate or ridged, 

 a. Shell conical, spire lengthened, sharply carinate. 



1. S. Cariniferum, Anthony. 15. S. p a g o d u ra, Lea. 



Showalterii, Lea. 16. S. p y r a m i d. a t u m, Shutt. 



2. S. castaneum, Lea. 17. S. Wetumpkaense, Lea. 



<S. ornata, Anth. 



S. pagoda, Lea, of Reeve. 



b. Shell conic-cylindrical ; spire obtuse, not carinate. 



3. S. o v o i d e u m, Shuttleworth. 18. S. Alabarnense, Lea. 



19 S. Anth o ny i, Lea. 



4. S. e x c i s u m, Lea. 20. S. b a b y 1 o n i c u m, Lea. 



Spillmanii, Lea. 



c. Shell globosely-ovate, spire moderate. 



5. S. p u m i 1 u m, Lea. 21. S. B u d d i i, Lea. 



Olobosum, Lea. S. funiculatum, Lea. 



Alabarnense, Lea, of Reeve. S. pagodum, Lea, of Reeve. 



Showalterii, Lea, of Reeve. 



2. Shell smooth, 

 d. Shell elliptic. 



6. S. e 1 1 i p t i c u ra, Anthony. 



7. S. laciniatum, Lea. 



e. Shell quadrately cylindrical. 



8. S. ampin m, Anthony. 22. S. d em iss um, Anth. 



9. S. n u c u 1 u m, Anthony. S. Hartmanii, Lea. 



23. S. const rictum, Lea. 

 S. rectum, Anth. 



* The Schizostnmx contain two nearly equal groups, characterized respectively by a narrow 

 direct, and an oblique, short, wide .slit. 



In the above table the opposite gpei-ies in the two groups are generally exactly similar except 

 in the character of the slit I 



