NOTICES OF NEW BOOKS. 223 
symmetrical mouth, and with one eye on each side ; they there- 
fore keep their body in a vertical position when swimming. As 
they grow they live more on the bottom, and their body, during 
rest, assumes a horizontal position; in consequence, the eye of 
the lower side moves towards the upper, which alone is coloured; 
and in many genera the mouth is twisted in the opposite 
direction, so that the bones, muscles, and teeth are much more 
developed on the blind side than on the coloured. In a great 
number of other Teleostei certain bones of the head show a very 
different form in the young state. The curious changes which 
the Sword-fish (Histiophorus) undergoes from the young to the 
adult condition are described (pp. 173—175), with illustrations. 
The flesh of some fishes, says Dr. Giinther, is at times, or con- 
stantly, poisonous. When eaten, it causes symptoms of more or 
less intense irritation of the stomach and intestines, inflammation 
of the mucous membranes, and not rarely death. All, or nearly 
all, these fishes acquire their poisonous properties from their 
food, which consists of poisonous Meduse, Corals, or decomposing 
substances. Frequently, however, they are found to be eatable 
if the head and intestines be removed. In the West Indies, it 
has been ascertained that all the fishes living and feeding on 
certain coral banks are poisonous. In other fishes the poisonous 
properties are developed only at certain seasons of the year, 
especially at the season of propagation, as the Barbel, Pike, and 
Burbet, whose roe causes violent diarrhoea when eaten during the 
Spawning season. 
Poison organs are more common in the class of fishes than 
was formerly believed, but they seem to have exclusively the 
function of defence, and are not auxiliary in procuring food, as in 
venomous snakes. Such organs are found in the Sting-rays, the 
tail of which is armed with one or more powerful barbed spines. 
Although they lack a special organ secreting poison, or a canal 
in or on the spine by which the venomous fluid is conducted, the 
Symptoms caused by a wound from the spine of a Sting-ray are 
such as cannot be accounted for merely by the mechanical 
laceration, the pain being intense, and the subsequent inflamma- 
tion and swelling of the wounded part terminating not rarely in 
gangrene. The mucus secreted from the surface of the fish, and 
inoculated by the jagged spine, evidently possesses poisonous 
properties. This is also the case in many Scorpenoids, and in 
