16 LECTURE II. 



naturalists, and which is found in the mangrove 

 swamps. It can ascend trees like a chimney- 

 sweep, and this it does by only using a pair of 

 prickles from the gill-flaps, instead of elbows, 

 and thus it gains the tops of stems many feet 

 above high- water mark, picking off the flies that 

 alight on the tree it climbs up. 



But let us now turn to flying fish. There are 

 several different species of these, and they are 

 sadly persecuted, being pursued in the sea by 

 bonitos and other rapacious fishes, and take 

 flight when they are in danger from them. 

 While in the air, the frigate and other marine 

 birds make them their prey. It may seem to 

 you surprising that there should be flying fish 

 as well as creeping and climbing fish, and yet 

 they are known to exist. 



Many of you, no doubt, have heard of the 

 sea-cow. It appears a mass of blubber and al- 

 most incapable of motion, yet its fins are covered 

 with a sort of nails which enable it to crawl on 

 shore, assisted by its pectoral fin, and also to get 

 on the ice. I mention, this to prove to you that 

 the fins of these creatures are as curious as the 

 formation of the fish referred to, and that in both 

 cases the fins of the sea-cow, and the muscular 



