16 PROCEEDINGS OF THE ACADEMY OF [1894. 



cessoiy organs developed upon the genital system, differing in this 

 respect from the Zonitoldes section of G tstrodonta. The type of 

 Vitrea is H. crydalllna Miiller of Europe. There are a great many 

 generic synonyms, but part of the names quoted above are available 

 for sectional divisions. The American species must all be examined 

 to ascertain whether or not they possess a dart sac, as those having 

 this structure must be removed to the genus Gastrodoiita. I have 

 not had time to examine the soft parts of any of them. 



V. arborea Say. 



Monterey, Franklin Co., Pa., 64,696, S. E. cor. Franklin Co., 

 Pa., near Maryland line, 64,693. Foothills of Martin's INIt., Md., 

 64,694. Morgan Co., W. Va., opposite Hancock, 64,695. Also 

 collected at York Furnace, York Co., Pa., by Witmer Stone. 



V. electrina Old. 



Summit of North Mountain, west of Clear Spring, Washington 

 Co., Md., 64,836. Monterey, Franklin Co., Pa., 64,839. 



V. (Glyphyalinia) indentata Say. 



Monterey, Franklin Co., Pa., 64,838. Summit of North Moun- 

 tain, west of Clear Spring, Md., 64,837. Morgan Co., W. Va., op- 

 posite Hancock, 64,692. Also York Furnace, York Co., Pa. 

 (Stone). 



Genus GASTRODONTA Albers. 



1S50.— Gastrodonta Alb., Die Heliceen, p. 88. 



1857. — Gastrodonta Alb., Mai. Bl. IV, p. 91, type H. interna Say. 



1862. — Zojijfotdes Lehraann, Mai. Bl. IX, p. Ill, type Z. nltidus 



Miill. 

 1864. — Pset(do]iiialina Morse, Terr. Pulm. Me., p. 15, (for H. 



exigiia, mlnnscala, limatnla, etc.). 

 1869. — Ventrideris Binney and Bland, Laud and Fresh- water 



Shells of N. A., I, p. 292 (proposed for H. (jularis 



and H. snppressa Say). 



The shell is provided with internal teeth or lamellae in the typical 

 forms of this genus. In another group, consisting of G. ligera and 

 its allies there are no teeth, but a strong white callus upon the floor 

 of the last whorl. In the section Zonitoldes this callus is wanting, 

 and the whorls are rounded below. 



The prominent feature of the genitalia is the presence of a dart 

 sac containing a long curved calcareous dart, situated upon the va- 



