Notes on American Land Shells. 323 
SOME NOTES ON AMERICAN LAND SHELLS. 
No. II. 
By A. G. WerHersy, 
Prof. Geology and Zoology, University of Cincinnati. 
During the past summer I spent about twelve weeks among the moun- 
tains of North Carolina and East Tennessee, and in regions of special 
interest to the student of N. A. conchulogy, because of the number of 
new species of land shells so recently described from there by Mr. W. 
G. Binney, and to which list two more must now be added, the Patula 
bryanti, Prof. Harper, and the Helicodiscus jimbriatus. 
Roan Mountain rises to a height of 6,391 feet above sea level. It is 
composed entirely of metamorphic and plutonic rocks, the former dip- 
ping at a high angle to the southeast, and: the latter being thrust 
through them in various directions. The structure of the mountain is 
essentially monoclinal, and its present relief is the result of erosion. 
The slopes are heavily timbered to the very margin of the “ bald,” though 
the trees are stunted and dwarfed at the top, with the exception of the 
firs and balsams, which seem to have their normal habitat. Not- 
withstanding the large number of species which has been collected 
here, the number of individuals, except in a few cases, is comparatively 
small, and as the search for shells was prosecuted with very great 
vigor, by several members of my party, as well as by myself, J am 
able to speak authoritatively on this point. I wish, therefore, to put 
upon record the confirmation of a statement which I have pre- 
viously recorded in this JourNnaL, that regions of greatest diversity of 
types are not always regions populous with individuals. The forest 
on the slopes of this mountain are everywhere moist; the soil is exceed- 
ingly fertile, and the climate mild and equable. ‘These are conditions 
favorable to this kind of molluscan life, but there is an almost absolute 
dearth of limestone, and here may be found one of the causes for in- 
dividual scarcity. 
I have submitted my collections to Mr. Thomas Bland, of New York, 
the highest authority on American land shells, and the notes which 
follow will be made upon the names as given by him. I may remark 
that all these species were collected by me, personally, and that the 
station was in every case carefully observed. None of the shells ex- 
