THE ORIGIN OF THE OLDEST FOSSILS. 3G3 



Broa<lly stated, the history of each great line lias been like that of 

 the echinoderiiis and brachiopods. The oldest pteropod or lanielli- 

 branch or echinoderni or crnstaceaii or vertebrate which we know from 

 fossils exhibits its own tyjie of strncture with perfect distinctness, and 

 later intluences have done no more than to expand and diversify the 

 type, while anatomy fails to gnide ns back to the point where these 

 various lines met each other in a common source, although it forces us 

 to believe that the common source, once had an individual existence. 

 Embryology teaches that each line once had its own representative at 

 the surface of the ocean, and thnt the early stages in its evolution have 

 passed away and left no record in the rocks. 



If we try to call before the mind a picture of the land sui-face of the 

 earth we see a vast expanse of verdure stretching from high up in 

 the mountains over hills, valleys, and plains, and through forests and 

 meadows down to the sea, with only an occasional lake or broad river 

 to break its uniformity. 



Our i^icture of the ocean is an empty waste, stretching on and on 

 with no break in the monotony except now and then a Hying fish or a 

 wandering sea bird or a tioating tuft of sargassum, and we never think 

 of the oceaji as the home of vegetable life. It contains plant-like ani- 

 mals in abundance, but these are true animals and not plants, although 

 they are so like them in form and color. At Nassau, in the Bahama 

 Islands, the visitor is taken in a small boat, with windows of plate 

 glass set in the bottom, to visit the " sea gardens" at the inner end of 

 a channel through which the pure water from the open sea tiows 

 between two coral islands into the lagoon. Here the true reef corals 

 grow in quiet water, where they may l)e visited and exannned. 



When illuminated by the vertical sun of the Tropics and by the light 

 which is reflected back from the white bottom, the pure, transparent 

 water is as clear as air, and the smallest object 40 or 50 feet down is 

 distinctly visible through the glass bottom of the boat. 



As this glides over the great mushroom shaped coral domes which 

 arch up from the depths, the dark grottoes between them and the caves 

 under their overhanging tops are lighted up by the sun, far down among 

 the anthozoa or flower animals and the zoophytes or animal plants, 

 which are seen through the waving thicket of brown and purple sea 

 fans and sea feathers as they toss before the swell from the open ocean. 



There are miles of these "sea gardens" in the lagoons of the Baha- 

 mas, and it has been my good fortune to spend many months studying 

 their wonders, but no description can convey any conception of their 

 beauty and luxuriance. The general eft'ect is very garden-like, and the 

 beautiful fishes of black and golden yellow and iridescent-cobalt blue 

 liover like birds among the thickets of yellow and lilac gorgonias. 



The parrot fishes seem to be cropping the plants like rabbits, but 

 more careful examination shows that they are biting off the tips of the 

 gorgonias and branching madrepores or hunting for the small Crustacea 



