190 



FISHES. 



are found to be eatable if the bead and intestines be removed 

 immediately after capture. In the West Indies it bas been 

 ascertained that aU the fisbes living and feeding on certaiu 

 coral banks are poisonous. In other fishes the poisonous 

 properties are developed at certaia seasons of the year only, 

 especially the season of propagation : as the Barbel, Pike, 

 and Burbot, whose roe causes violent diarrhoeas when eaten 

 during the season of spawning. 



Poison-organs are more common ia the class of Fishes than 

 was formerly believed, but they seem to have exclusively the 

 function of defence, and are not auxiliary ia procuring food, as 

 in venomous Snakes. Such organs are found in the Sting-rays, 

 the tan of which is armed with one or more powerful barbed 



Flf 



, 98. — Portion of tail, witli spines, of Aetoiatis narinari, a Sting-ray 

 from the Indian Ocean, a, nat. size. 



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 inflammation 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 venomous properties. This is also 

 the case in many Scorpsenoids, and in the Weaver (Trachinus), 

 in wliich the dorsal and opercular spines have the same 



