52 Adaptations of Fishes 
Certain small catfishes known as stone-cats and mad-toms 
(Noturus, Schilbeodes), found in the rivers of the Southern and 
Middle Western States, are provided with special organs of 
offense. At the base of the pectoral spine, which is sometimes 
very jagged, is a structure supposed by Professor Cope to be a 
poison gland the nature of which has not yet been fully ascer- 
tained. The wounds made by these spines are exceedingly 
painful like those made by the sting of a wasp. They are, 
however, apparently not dangerous. 
Venomous Spines.—Many species of scorpion-fishes (Scor- 
pena, Synanceia, Pelor, Pterois, etc.), found in warm seas, 
as well as the European weavers. (Trachinus), secrete poison 
Fig. 86—Black Nohu, or Poison-fish, Emmydrichthys vulcanus Jordan. A species 
with stinging spines, showing resemblance to lumps of lava among which it 
lives. Family Scorpenide. From Tahiti. 
from under the skin of each dorsal spine. The wounds made 
by these spines are very exasperating, but are not often danger- 
ous. In some cases the glands producing these poisons form an 
oblong bag excreting a milky juice, and placed on the base of 
the spine. 
In Thalassophryne, a genus of toad-fishes of tropical America, 
is found the most perfect system of poison organs known among 
fishes. The spinous armature of the opercle and the two spines 
of the first dorsal fin constitute the weapons. The details are 
known from the dissections of Dr. Gunther. According to his* 
observations, the opercle in Thalassophryne ‘is very narrow, 
* Gunther, Introd. to the Study of Fishes, p. 192. 
