54 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



small bulrushes, lilies, aud other water plants; the pouds are of most 

 irregular and confusing shapes, so that it is a matter of much difficulty 

 to travel twice over the same route ; ponds may have wide connections, 

 narrow connecting channels almost entirely hidden by saw-grass, or may 

 be shut in by saw-grass completely. Oftentimes a tall man is unable to 

 see a pond close at hand, so thick and high is the saw-grass. Scattered 

 about in this sea of grass are islands of bushes and trees, called Keys. 

 These keys seem to owe their origin to an accumulation of vegetable 

 matter which may appear some inches above water level, during the dry 

 season becoming partially dry (Plate XXIII. Fig. 2). During a night's 

 sleep upon them one's bed is liable to settle to water level, and it is a 

 common experience to break through to the knee in walking over them 

 without feeling a firm foundation ; it is probable that the mat of grass 

 roots or peat is what stops one's downward progress. 



Origin of the Oolite. — The low undulations of the land surface in the 

 pine belt can scarcely be accepted as evidence of former dunes. They 

 would well accord, however, with the inequalities of a sea floor like the 

 present one between the keys and the mainland. The cross-bedding 

 and oolitic structure favor neither water nor wind as the primary agent 

 in the construction of the rock. Therefore, since the land appears to be 

 very young, being almost without soil and surface drainage ways, the 

 topography favors an origin for the limestone in water. Elevation was 

 apparently accompanied by slight folding, thus giving opportunity for 

 the pine belt to develop and favoring the formation of a line of keys, in 

 shallower water in the Everglades, approximately parallel with the edge 

 of the pines and distant a few miles. This line of keys in the Ever- 

 glades diverges southwestward from the pine belt just as the pine belt 

 does from the elevated reefs. 1 



i It seems to me that Mr. Griswold is mistaken in ascribing an aqueous origin 

 to the oolitic limestone he collected from the Everglades. From what I saw my- 

 self of this limestone along the shore of Key Biscayne Bay, the rocks, which are 

 the same as those collected from the inland by Mr. Griswold, consisted entirely 

 either of patches of honeycombed aiolian rock or of weathered elevated reef coral 

 limestones, the aeolian rock having been blown into sinks, as I observed it at 

 Boca Chica, so as to fill them, and as dunes rising to eighteen or even twenty feet 

 on higher parts of the mainland. The decomposition and disintegration of the 

 Everglades Beema to me to indicate merely a later stage of disintegration, and one 

 similar in every way to that going on between the keys and the present shore of 

 the Florida mainland, a disintegration and decomposition affecting rocks of the 

 same age and of the same constitution, — viz. Beolian and elevated coral reef rocks, 

 — and going on along the edges of the greater or smaller sinks, filled with seolian 

 Bands, which separate the different parts of the elevated coral reef. Some of the 



