Order V. gangetic fishes. 139 



it any communication with the throat, mouth, or any consi- 

 derable gland ; nor, so far as I could observe, does it ever en- 

 large within into any thing like a hollow sack. This slit, al- 

 though somewhat differently situated, has an affinity with the 

 subocular sack of some species of the ruminant quadrupeds, al- 

 though I cannot state the use of such an organ in either class 

 of animals. 



Several species have two apertures in the vent, one proba- 

 bly an organ of procreation, and the other of digestion, I do 

 not, however, know that both sexes of the same species have 

 this double aperture ; and suspect that it belongs only to the 

 male, as I have several times observed a fleshy substance pro- 

 truded from the foremost aperture, which I considered to be a 

 kind of penis, although I never ascertained the point by dis- 

 section ; nor did I notice it in every individual that I observ- 

 ed with two apertures. 



A great many species are provided with a strong prickle in 

 the first fin of the back, and in each pectoral fin. These 

 prickles are no doubt formidable weapons of defence, as they 

 are capable of inflicting severe wounds on any enemy that at- 

 tempted to seize the animal which they guard ; yet in gene- 

 ral, every time that they are employed, the animal must suffer 

 considerably, as, in most of the species, these prickles termi- 

 nate in a flexible substance resembling somewhat whalebone ; 

 and, before the prickle can penetrate an enemy, this flexible 

 point, which supports part of the membrane, must be broken. 

 Although, therefore, it is probable, that, in case of such acci- 

 dents, the flexible part may be soon reunited to the prickle ; 

 yet it is not likely that the animal should have recourse to the 

 use of such a weapon, except in emergency, and perhaps ne- 

 ver as a weapon of attack. These weapons are indeed so for- 

 midable, not only from their strength, but from their being in 



