iliTJOTfi-MSH. 
13 . 
of M. Lamouroux, that if the fucus adhere to the rocks 
with the greatest firmness before its fructification, it separ 
rates with great facility after that period, or during the sea- 
son which suspends its vegetation like that of the terrestrial 
plants. The fish and mollusca which gnaw the stems of the 
seaweeds no doubt contribute also to detach them from their 
roots. 
Prom the twenty-second degree of latitude, we found the 
surface of the sea covered with flying-fish,* which threw 
themselves up into the air, twelve, fifteen, or eighteen feet, 
and fell down on the deck. I do not hesitate to speak on 
a subject of which voyagers discourse as frequently as of 
dolphins, sharks, sea-sickness, and the phosphorescence of 
the ocean. None of these topics can fail to afford in- 
teresting observations to naturalists, provided they make 
them their particular study. Nature is an inexhaustible 
source of investigation, and in proportion as the domain of 
science is extended, she presents herself to those who know 
how to interrogate her, under forms which they have never 
yet examined. 
I have named the flying-fish, in order to direct the atten- 
tion of naturalists to the enormous size of their natatory 
bladder, which, in an animal of G' i inches, is 3'6 inches long, 
0'9 of an inch broad, and contains three cubic inches and a 
half of air. As this bladder occupies more than half the size 
of the fish, it is probable that it contributes to its lightness. 
We may assert that this reservoir of air is more fitted for 
flying than swimming; for the experiments made by M. 
Provenzal and myself have proved, that, even in the species 
which are provided with this organ, it is not indispensably 
necessary for the ascending movement to the surface of the 
water. In a young flying-fish, 5 - 8 inches long, each of 
the pectoral fins, which serve as wings, presented a sur- 
face to the air of 3^ square inches. We observed, that 
the nine branches of nerves, which go to the twelve rays 
of these fins, are almost three times the size of the nerves 
that belong to the ventral fins. When the former of 
these nerves are excited by galvanic electricity, the rays 
which support the membrane of the pectoral fin extend with 
five times the force with which the other fins move when 
* Exocoetus volitans. 
K 2 
