Histcry und Progress of Comparative Anatomy. SjOtS^ 



by gills which are pervious to air and water, yet exclude the 

 latter while they admit the former. That this mode of respira- 

 tion is connected with the small proportion of blood and tlw^ 

 lower temperature, he infers from the fact, that aquatic animals 

 which are warm and abound in blood, as the dolphin, seal, and 

 whale, respire the air by means of genuine lungs ; and he adds^ 

 that in those which have gills, the swimming bladder is perhaps 

 Calculated to answer a similar purpose. He then describes the 

 distribution of the bronchial tubes in man, land animals, an(l 

 the fishes which breathe by lungs ; in other words, in the Mam-^ 

 malia ; in all which he takes care to say the structure is the 

 same, with this exception, that, in the Cetacea and Amphibia^ 

 the lung is not so soft and spongy as in the terrestrial Manh 

 inaliay but is thick and fleshy, probably because the occasional 

 admission and expulsion of the water required such a peculia- 

 rity. Gills, on the other hand, are peculiar to fishes ; and of these 

 some are covered, as in the species of lupus or pike ; the aurata^ a 

 species of dory ; the^caH, cynaedi, and tunny (ihynni) ; anphias^ 

 sword-fish ; the sea-pike or spit-fish (sphyrana), &c. ; while 

 others, as all the cartilaginous fishes, except the sturgeon, are 

 uncovered. He also remarks the tubular gills, or branchial 

 perforations of the lamprey, eel, and similar fishes, and rectifies 

 the mistake of Pliny, who asserts that the muraena^ a species of 

 lamprey probably, is void of gills. The heart he distinguishes 

 into three parts, an inferior, a middle, evidently the ventricle^ 

 and the superior, which is manifestly the bronchial artery, and 

 which he properly represents to be au arterial tub*, r^wryw*" 



4 In the alimentary canal he recognises the longitudinal and 

 transverse folds of the gullet, and the peculiarities of the 

 stomach in shape and size. Those of the mullet and sturgeon 

 he accurately represents to be fleshy and muscular. The pyloric 

 or duodenal appendages also, he remarks, vary in number, and 

 are confined to those which have gills. He rather ingeniously 

 observes, on the use of these bodies, that, as the temperature of 

 fishes is low, the food distributed into these appendages may be 

 more readily acted on than if it was in one cavity. 



The want of genuine kidneys and a bladder, he remarks in 

 proper fishes, birds and reptiles. Those which breathe by 

 lungs, however, that is, the cetaceous and amphibious animals 



