The natural history of fishes, amphibians, & reptiles, or monocardian animals . he head, which only leaves a smallslit or spiracle (a), by which they breathe. This latteris a universal character; and is the more to be valued,since, whatever eel-shaped or anguilliform fishes arefound scattered in other types, even though they mayhave soft fins, or only the rudiments of ventrals, yetthey never have these two characters united with thespiraculated aperture. (186.) The Apodes, as we have already shown,occupy that part in the series of fishes which markthe transition from the cartilaginous to the o
The natural history of fishes, amphibians, & reptiles, or monocardian animals . he head, which only leaves a smallslit or spiracle (a), by which they breathe. This latteris a universal character; and is the more to be valued,since, whatever eel-shaped or anguilliform fishes arefound scattered in other types, even though they mayhave soft fins, or only the rudiments of ventrals, yetthey never have these two characters united with thespiraculated aperture. (186.) The Apodes, as we have already shown,occupy that part in the series of fishes which markthe transition from the cartilaginous to the no definite character for them is to be derivedfrom the nature of their skeleton, except this, indeed,—that a gradual progression in its development may betraced in the different families, from the semi-carti- p 3 21 CLASSIFICATION OF FISHES. laginous structure of Lophius, to the bony skeleton ofmost of the eels : and. at the same time, a falling offto the faintest indication of the vertebral column, as inMyxene glutinosa (Jig. 3Q.): which all authors agree in. placing near to the worms. The order, however, standsin no need of any additional characters than those we havepointed out. The common eel may be cited as the mostperfectly typical of the whole; while the eel-shapedlampreys, as all writers agree, indicate the manner inwhich the class of fishes blends into that of the annuloseanimals, or insects. It may further be remarked thatthis, no less than the other two aberrant orders of fishes,affords us no example of true deciduous scales. Never-theless, as the Apodes blend into an order where thissort of covering is almost universal, we now begin tosee their incipient commencement. Many of the eels,for instance, have very small scales, but so covered overby their thick and fat skin, that they are scarcely visiblewhen the animal is alive. True scales, on the contrary,are always placed upon the surface of the skin, and, asevery one knows, may be easily detached, or
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Keywords: ., bookcentury1800, booksubj, booksubjectfishes, booksubjectreptiles
