On the Deformities of some Tennessee Helices 155 



pressa, Say. Beside the forms familiar to our collectors about Cincin- 

 nati, there occurs one in the southern part of Kentuck}*, and which 

 seems to be distributed down the Cumberland plateau and its outliers 

 nearl}' to Emerj' Gap, smaller in size, thinner in texture and very heavi- 

 ly ribbed, like the H. [Patula) alternata, var. mordax, inhabiting 

 the same range. As is the case with the variety of this species inhab- 

 iting our neighborhood, it is occasionally found about old logs, but its 

 favorite station seems to be among the broken rocks forming the talus 

 of the mountain cliffs. Here, in wet weather, they may be collected by 

 thousands, as they could have been at one time on certain stone walls, 

 and in certain cellars of this cit}^; localities that, owing to the active 

 search of unsatisfied gormands, have been practicall}" exhausted, a fate 

 luckily never in store for these mountain fastnesses. 



In Union couut}^, Tennessee, and extending southward through the 

 great eastern vallej', we find a very difi"erent variet}^ of the same spe- 

 cies. The shells are much larger than either of the other varieties, en- 

 tirelj' wanting the ribbed character, and exhibiting much fainter lines 

 of growth than characterize the Cincinnati form. This variety I found 

 this summer inhabiting the caves and rock crevices of Lookout Moun- 

 tain, where it is removed from its normal range. In considering the 

 causes which have led to these wide variations, we may possibly ac- 

 count for the larger growth of the Cincinnati and East Tennessse Val- 

 ley varieties, by quoting the old theory of limestone regions. I have 

 elswhere shown, however, that many of our common species reach their 

 maximum growth in sandstone regions, though the larger size seems to 

 be somewhat compensated by the paucity' of individuals. Even this rule 

 fails, in fact, in many caaes. But as to the cause of the development 

 of the ribs, and the unnatural flattening of the spire, it is quite impos- 

 sible to ofter any certain conjecture. However, the result of an hour's 

 collecting, in one of the many tali along the eastern front of the Cum- 

 berland plateau, presented a few curious features. These specimens 

 were hastily and indiscriminate!}' picked up from among hundreds 

 crawling over the rocks, thrown into alcohol, and not examined until 

 my return. So soon, however, as I began looking at them more care- 

 fully, I was struck with the number and extent of the deformities 

 which the shells exhibited. The number of specimens is 129, and the 

 number of deformities 43, or 33^ per cent. Manj^ of the specimens ex- 

 hibit two deformities, one of which affects one part of the shell, an- 

 other quite a different part. I have, therefore, tabulated the injuries, 

 as follows : 



1. Number of deformities of spire, 17. 



2. " " " " umbilical region, 15. 



3. " '' " " aperture, 18. 



