VENOMS IN THE ANIMAL SERIES 291 
placed on the back of the fish. The wound is very painful, and is 
accompanied by a series of alarming symptoms, which sometimes 
terminate fatally: fishermen are consequently much afraid of it. 
There are a large number of species of this fish, peculiar to 
different regions. Synanceia brachio (fig. 101), the largest specimens 
of which attain the length of 45 cm., is the most common form in 
the Tropical Pacific. 
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Fig. 101.—Synanceia brachio, var. verrucosa. (After Savtschenko.) 
The spiny rays of the dorsal fin of Synanceia are sharp-pointed, 
stout in the middle, and provided on each side with a small canal 
hollowed out in the thickness of the spine. Towards the middle of 
the latter there is attached a little double sac, or kind of closed pouch, 
which, on being compressed, allows the venom to escape in a thin 
jet which flows into the grooves of the spine. The expulsion of the 
venom is therefore not a voluntary act on the part of the fish; in 
order that it shall take place, pressure must be applied to the sacs in 
which it is contained. 
This venom, when extracted from the glands, is limpid, bluish, 
and slightly acid. When introduced into the tissues, it produces very 
acute local pain, which extends throughout the affected limb. The 
