1912.] NATURAL SCIENCES OF PHILADELPHIA. 135 



of space, light, and edaphic relations. A very slight difference in the 

 soil, drainage, depth below the general surface of the adjoining 

 pine land, amount of soil or standing water, amount of light which 

 penetrates through the close stand of surrounding pine trees, makes 

 a difference in the vegetation that fills the different banana holes. 



In all, twenty-three plants were found in seventeen different 

 banana holes investigated in a region where they are common, 

 namely, between Naranja and Princeton in South Florida. The 

 following is a list of the species and their relative abundance: Sabal 

 palmetto (12), Anona glabra (11), Chrysobalanus pellocarpus (8), 

 Sagittaria lancijolia (8), Myrica cerifera (6), Per sea pubescens (4), 

 Yitis munsoniana (4), Proserpinaca platycarpa (4), Cladium effusum 

 (4), Ilex cassine (3), Cephakmthus occidentalis (S),Salix longipes (3), 

 Phlebodium aureum (2), Isnardia natans (2), Polypodium polypo- 

 dioides (1), Typha latifolia (1), Phragmites phragmites (1), Smilax 

 laurifolia (1), Quercus virginiana (1), Metopium mctopium (1), 

 Morinda roioc (1), Conoclinum dichotomum (1), Willugbaeya scandens 

 (1). Of these species nine are trees; two, shrubs; three are lianes; 

 several are epiphytes; four are rooting aquatics and two are sub- 

 merged aquatics. 



The origin of these banana holes and the character of the native 

 vegetation with which they are filled suggest the origin and nature 

 of the larger areas of deciduous subtropic and tropic forest trees 

 known in the South as hammocks. As the banana holes exist in all 

 sizes from those which are a meter in diameter to those which cover 

 several hectares, no sharp distinction can be made between the 

 vegetation of the larger banana holes and the smaller hammocks 

 which occur in the same region. Presumably the hammocks have 

 had a similar origin as the banana holes by starting in a shallow, 

 basin-shaped hollow of the prevailing oolitic limestone. This 

 hollow has filled gradually with leaf -mold and sand liberated by the 

 solution of the surrounding lime rock of which sand is a constituent 

 until a sandy loam soil is formed in which the tropic forest trees find 

 suitable conditions for growth. Once the hammock vegetation has 

 established itself, it becomes self-perpetuative and forms a climax 

 forest, which becomes an exclusive type gradually encroaching upon 

 the area of country occupied by the slash pine, Pinus caribaea, which 

 with its associates forms an ancient and successful type of forest 

 holding well its own against other competing types of vegetation. 



Frederick W. True, LL.D.: "A New Species of Delphinodon." 

 Illustrated.* 



Dr. Frederick W. True gave an account of a new species of fossil 

 porpoise from the Miocene formation of Maryland, belonging to 

 the genus Delphinodon, for which the name of Delphinodon dividum 

 is proposed. The U. S. National Museum was engaged in 1908 

 and 1909 in making collections of cetacean remains from the 

 Calvert Cliffs, Maryland, and obtained several skulls and fragments 

 of skulls, many limb bones, and large numbers of vertebrse. In 



