^^89^^'] PROCEEDINGS OF THE NATIONAL MUSEUM. 749 



is so restricted and peculiar in its distribution, that, considered in con- 

 nection Avitli tlie fossil exanii)les, it may l)c regarded as obsolescent or 

 as an interesting survival of the extraordinary physical changes of the 

 John Day ejioch, and the apparent absence of Mesodori in the region 

 heretofore indicated, may be due to its absolute obliteration through 

 similar causes during the middle or later tertiary periods as well as to 

 still later i)hysical changes. 



Helix (Mesodon) dentifera Biiiiiey. 



One dead, fresh example. 

 Washington, Miss. ; Vernon Bailey. 



Mr. Bailey has carried this form quite far to the South. Its range 

 has heretofore been given as from Maine to North Carolina. 



Helix (Mesodon) thyroides Say. 

 Var. hurculfiild (Jmild. 



Several examples. 



Washington, Miss, (one example living); near Marble ('ave. Stone 

 County, Mo. (three specimens), occurring on the sidchills, and at 

 Houma, La. (nine dead specimens); Yernon Bailey. 



Mr. Binney says of fhi/roidcs: "A post-i)liocene species now found 

 all over the eastern i)rovince. The variation in size is very great- 

 The small or bucctdentus form of this species is usually that found in 

 the Southern States. Both the larger and smaller forms exhibit a 

 small parietal callosity or tooth, and the shell is also variable in the 

 umbilical feature." Binney credits it to Washington County, Tex., 

 and Mr. W. L. McDaniel, of Tyler, Tex., has collected the hucculenta 

 form in Williamson County in that State. 



Some examples of thyroides-hucculenta that I have inspected are exter- 

 nally very close to occasional individuals of the so-called ptychophora^ 

 from CoBur d'Alene, Idaho. 



Geuus TRIODOPSIS Rafiiiesiiue. 



Helix (Triodopsis) inflecta Say. 



Two specimens, dead. 



Stone County, Mo. ; Vernon Bailey, July, 1892. 



The above examples were found on the slopes of the hills near 

 Marble Cave. Tlie species inhabits a large territory, extending from 

 the Atlantic seaboard westerly to the valley States of the Ohio and 

 Mississippi rivers, and southwesterly to Texas. A well marked and 

 easily recognized form. 



Helix (Triodopsis) Levettei Hlaud. 

 Ten examples. 



Fort Huachuca, Ariz., Dr. A. K. Fisher, May 14, 1892. 

 The specimens colle<'ted by Dr. Fisher, thougli much larger tlian the 

 type, having from one-and-a-half to two-and-a half more whorls, agree 



