i8o 



Adaptations of Fishes 



Certain small catfishes known as stone-cats and mad-toms 

 (Noturiis, Schilbeodcs), 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- 

 pcrim, Syiiauccia, Pclor, Ptcrois, etc.), found in warm seas, 

 as well as the European Aveavers {TracJiiiius), secrete poison 



'.f^ 



"'•^'•iiyf 



Fig. 134. — Black Nohu, or Poi.son-fish, Emmjjdrichthys ndcnniis .Jordan. A species 

 with stinging spines, showing resemlilance to kimps of lava among which it 

 lives. Family Scorpcmidw. 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 Thalassopliryuc, 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 Tlialassopliryuc "is very narrow, 



* Gunther, Introd. to the Study of Fishes, p. 192. 



