THE GREAT MUSEUMS OF BRITAIN. 79 



gave an account of the system of cellular cavities or ' air- 

 receptacles ' which are connected with the lungs of birds, 

 and which in turn communicate with the interior of 

 many of the bones. He also published a paper on the 

 singular ' Gizzard Trout ' or ' Gillarroo Trout ' ( Salmo 

 stomachicus) of Ireland. 



In 1775, he published a series of observations on the 

 great electric eel (Gymnotus electricus} of South America, 

 and described the anatomical structure of the electrical 

 organs in this fish. 



Both in this year and in 1877, ne published in the 

 'Philosophical Transactions' a series of observations on 

 the temperature of animals and plants; and in the latter 

 year he gave to the world the second portion of his 

 ' Treatise on the Natural History of the Teeth.' 



Between 1779 and 1785, he published various zoological 

 papers in the 'Philosophical Transactions,' the most 

 important being one on the organ of hearing in fishes. 



In 1786, appeared his well-known 'Observations on 

 certain parts of the Animal (Economy,' in which he not 

 only republished the papers above alluded to, but added 

 various others, dealing with the secretion in the crop of 

 breeding pigeons for the nourishment of their young; 

 on the colour of the pigmentum nigrum in different 

 animals; observations tending to show that the wolf, 

 jackal, and dog belong to a single species ; on the 

 structure and economy of whales ; and various more 

 strictly anatomical or surgical memoirs. 



Subsequent to the publication of the 'Animal 

 (Economy.' Hunter published comparatively few zoo- 

 logical papers, though various observations which he 



