346 Canadian Record of Science. 



and the keys are simply small islands, usually without veg- 

 etation, though some of the larger ones are densely covered 

 with plant life. While the water over the reefs is nowhere 

 deep, not often exceeding six fathoms, just ouside them the 

 ocean has great depth. This abrupt change partially ex- 

 plains the danger to mariners, and shipwrecks are still too 

 common. 



We were bound for Green Turtle Key, which is separated 

 from Abaco by about two miles of shallow water, one might 

 say a sort of lagoon. This is the largest of the keys, measuring 

 about a mile in length and less than a quarter of a mile at 

 its widest part. Most of the small keys are uninhabited, 

 but Green Turtle Key has a population of about 600. 



The water over the " bank " or submerged coral formation 

 is termed "white," except when green plants or colored 

 alga? grow on the bottom, owing to its remarkable clearness. 

 But viewed at a little distance, the surface of the water pre- 

 sents a beauty and variety of color related to the arrange- 

 ment of clouds, etc., which it is impossible to express in 

 words, and which a series of paintings might portray, though 

 very inadequately. 



Such is the transparency of the water, that with a " water- 

 glass," objects lying on the bottom can be clearly discrim- 

 inated at a depth of 4-5 fathoms ; in fact we were accustomed 

 to indicate by this means to our native diver exactly what 

 we wanted him to bring up, a plan which was uniformly 

 successful. 



Having rented one of the largest houses on the key, it 

 was fitted up as a laboratory and dwelling place combined. 

 Our stay lasted through the month of June, which was an 

 exceedingly busy time for us ; we were in a new world, and 

 daily fresh objects presented themselves for examination. 



The rest of this paper will be devoted in great part to 

 illustrating how largely the phenomena which have been asso- 

 ciated with the formation of coral islands may be illustrated, 

 in one small area. Here we find at once the requisite 

 temperature (not below 68°), the clear water and the shallow 

 depth, the conditions under which the coral animal flour- 

 ishes. The teeming life now there explains the results of that 



