1889.] NATURAL SCIENCES OF PHILADELPHIA. 131 



or two species each, another third by five species or less. Nearly 

 two-thirds of the genera have but one representative. 



In order of importance, or number of species, the families are 

 LeguminoscB, fifty-three sp. ; Euphorbiacece, thirty-five sp. ; Com- 

 posite, thirty-two sp.; Graminece, thirty-two sp. ; Rubiacece, twenty- 

 three sp. ; Malvacece, eighteen sp. The genera having the largest 

 number of species are Oroton, Epidendron, Euphorbia, Passiflora 

 with eight species each ; Acacia, Cassia, Citrus, Eugenia, Ipomoea, 

 Solanum and Tillandsia, with six species each, and Anona, Cereus, 

 Cyperus, Eupatorium, each with five species. Nearly one-third of 

 the total number of species are of economic value; of those possess- 

 ing medicinal properties there are forty-five astringents, thirty-four 

 tonics, twenty-five purgatives and twenty-one diuretics. 



A comparison of the Bahama— phsenogamic flora with that of the 

 Bermudas shows eighty-two families and one hundred and ninety- 

 five species common to the two groups of islands. 



While a large per centage of the flora is undoubtedly common to 

 Florida and the neighboring islands of the West Indies, fully one- 

 third of the species listed may be considered indigenous. 



Unfortunately no tract similar to the "Walsingham tract" of the 

 Bermudas has yet been found, in which the indigenous vegetation 

 of the group remains undisturbed in the possession of the orginal 

 surface. 



The present rocks are jeolian in formation, and the contained 

 fossils resemble present species, facts which indicate the recent 

 character of the Bahamas. 



That the older vegetation has been exterminated by wind and 

 water erosion and by subsidence, and that it, in its turn, grew upon 

 a surface of seolian origin is well shown by the present state of Booby 

 Island and similar barren Cays. Here the surface is covered by 

 grotesque excrescences produced by the wearing away of the softer 

 portions of the rock. Among these projecting masses, many are 

 tubular, the lumen of the tubes ranging from a fraction of an 

 inch to over a foot in diameter. These tubes bifurcate and branch 

 in various ways, and at first sight suggested to the speaker the idea 

 that they might be fulgurites. Close examination shows that the 

 rock of which thev are formed consists of minute water-worn grains 

 of calcareous material, comminuted coral and shell, cemented com- 

 pactly together ; in fact, they resemble in structure the rocks of the 

 fertile islands. They are, however, very much hardened on the inner 

 surface and a distinct zone of harder substance is apparent upon 

 fresh transverse fracture. 



This vitreous appearance, together with evidence that the 

 tubes had been formed while the sand was in an uncompacted con- 

 dition, recalled Darwin's description of fulgurites found in a similarly 

 exposed locality near the La Plata 1 and those found at Drigg 



1 Journ. of Researches into the Nat. Hist, of countries visited during the Voy- 

 age of H. M. S. Beagle, Vol. I, p. 76. 



