ADDITIONAL NOTE ON HELICINA OCCULTA 235 



from Virginia, 111., is also manifestly an error. The same probably 

 applies to Dr. A. Binney's report of the same species from Ohio. 1 



Neither recent nor fossil H. orbiculata extends northward to the 

 border of the Kansan drift, both reaching almost the same latitude, 

 that of the southwestern part of Kentucky. It is, therefore, decidedly 

 a southern species, which has never been found in any condition in 

 colder regions, and it is an abundant fossil in the southern loess. 

 Indeed, the genus Helicina is almost wholly tropical, and before the 

 habits and distribution of modern H. occulta were understood, the 

 presence of a representative of this genus in the loess was looked upon 

 as evidence that the climate was once warmer than at present. In 

 this connection it may be of interest to read Dr. A. Binney's observa- 

 tions on this point, made more than half a century ago in connection 

 with a discussion of the fossils of the Wabash River loess. 2 As 

 the work in which it appears is not easily accessible, the material 

 portion is quoted in full: 



As the genus Helicina belongs mostly to inter-tropical regions, and has rarely 

 been met with in a recent state in so high a latitude as that occupied by these 

 fossils, a good deal of importance has been attached to its occurrence here as 

 indicating such a change of climate as has been alluded to. But this supposition 

 creates more difficulties than it obviates, for the numerous species of other genera 

 found in company with the species in question, and which live at this time in the 

 same district in which the fossils are situated, must, according to this view, have 

 also been adapted to a warmer climate than the present, though they do not now 

 exist in southern latitudes, and therefore a very considerable change in their 

 habits must have since taken place. Notwithstanding the facility with which 

 the terrestrial mollusks accommodate themselves to the physical influences which 

 act upon them, such a change is not consistent with what we know of their history, 

 and hence the most reasonable conclusion is that the climate in which they lived, 

 from the days when the multitudes which now compose the mass of the fossil beds 

 were in the enjoyment of life upon the surface of the earth, to the present time, 

 has remained essentially the same. 



Dr. Binney did not in his day, of course, take into account the inter- 

 vals between the several loesses, during which it is more than probable 

 that the climate was severe. With this modification his statement 

 concerning the climate is still further borne out by the species under 

 discussion, for it is now known that the habits of H. occulta are essen- 



1 Terrestrial Air-breathing Mollusca of the United States (1851), Vol. II, p. 353. 



2 Ibid., Gould's ed., Vol. I (185 1), pp. 182, 183. 



