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recently, but having observed a new structure occupying the 

 grooves in the spines, winch appears to be an organ destined 

 to secrete a specific poison, I have willingly given up the 

 doubtful for what appears to be a certain cause. 



It was only on the 11th of May last, that, in making a 

 Microscopic examination of the spine and membrane, I noticed 

 this structure for the first time, but, owing to its being a mutila- 

 ted fragment, and to its not having been immersed in spirit, I 

 did not appreciate its importance until the following day, when 

 Dr. Inman, who kindly undertook to examine some fishes for 

 me after having carefully scrutinized them with his beautiful 

 glasses and practised eye, called my attention to the same 

 structure, which he had seen in a more perfect state, and whieh 

 I think proves to be a true poison gland. 



Dr. Inman was fortunate enough, not having an immediate 

 opportunity of examining the fishes in their fresh state, to 

 immerse them in spirit and water, in consecpience of which the 

 gland became more opaque and denser, nor did it separate from 

 its natural situation during manipulation. I always had fresh 

 fishes at hand, and in preparing the parts for examination, 

 without having used spirit, must always have torn the gland 

 from its usual resting place. 



The stinging apparatus of each operculum consists of the 

 spine, the glandular structute, and the regumentary membrane 

 which covers in both. The opercular spine is about half an 

 inch long ; when examined under the microscope, it has the 

 deceptive appearance of being channelled in the centre, and 

 the deception arises from the convexity of both sides and the 

 transparency of the bony structure. There is no tubular cavity 

 in the spine, ordinarily, though in rare instances a deficiency 

 of its substance in the middle exists ; but this does not appear 

 to have any connexion with the stinging apparatus. Both the 

 upper and under ridges are channelled out into grooves, each 

 of which penetrates nearly one-fourth part of the way through 

 the spine. Each groove is formed by two ridges or lamina of 



