142 PROCEEDINGS OF THE ACADEMY OF [March, 



The evidence advanced to prove mimicry in the Papilios was 

 considered inconclusive. Other cases of so-called mimicry in the 

 butterflies were regarded as being brought about by environmental 

 conditions, such as vertical distribution and desert distribution. 



Spencer Trotter, M.D.: " The Faunal Divisions of Eastern North 

 America in Relation to Vegetation."* 



Vegetation is more directly concerned in the problem of faunal 

 distribution than are the factors of heat and moisture. These, of 

 course, control vegetation, but soil is a more important control factor. 

 Topography likewise exerts a considerable influence. Zonal 

 arrangement of faunas is unnatural. On this basis of the vegetation 

 control, the following outline of Faunal Areas is submitted as best 

 expressing the known facts: 



I. The Sub-Arctic Fauna. 



(a) Barren Ground Type. 



(b) Tree-limit Type. 



II. The Atlantic Forest Fauna. 



(a) Coniferous Forest Type. 



(b) Deciduous Forest Type. 



III. The Coastal Plain Fauna. 



(a) The Alluvial Forest Type. 



(b) The Marshland Type. 



(c) The Pine Barren Type. 



IV. The Grassland Fauna. 



(a) The Prairie Type. 



(b) The Steppe Type. 



V. The Plateau Fauna. 



(a) The Cactus Desert Type. 



(b) The Mountain Forest Type. 



T. Wayland Vaughan, Ph.D.: "Rate of Growth of Stony Ccrals." 

 Illustrated. (No abstract.) 



Henry A. Pilsbry, Ph.D. : "On the Tropical Element in the Mollus- 

 can Fauna of Florida."* 



A sketch of the successive non-marine faunas of the region was 

 given and the genesis of the several elements composing the molluscan 

 fauna was traced. A Mexican group of forms was recognized and 

 evidence was adduced to show that they entered southern Florida 

 at the close of Miocene or very early in Pliocene time. Antillean 

 species were held to be of later advent in Florida. The probability 

 that they had been carried from Cuba by hurricanes was discussed. 

 The various points were illustrated by lantern slides of shells and 

 maps. 



The session closed with a beautifully illustrated communication 

 on "The Photography of Wild Birds," by William L. Baily. (No 

 abstract.) * 



