^18 Professor Owen's Teleology of the Skeleton of Fishes, 



creative forces, tlie soul-expanding appreciations of the final purposes 

 of the fecund varieties of the animal structures by which we are 

 drawn nearer to the Great First Cause. They see nothing more in 

 this modification of the skeleton, which is so beautifully adapted to 

 the exigencies of the highest organized of fishes, than a foreshewing 

 of the cartilaginous condition of the reptilian embryo in an enormous 

 tadpole, arrested at an incomplete stage of typical development. But 

 they have been deceived by the common name given to the Plagiosto- 

 mous fishes; the animal basis of the shark's skeleton is not cartilage ; 

 it is not that consolidated jelly which forms the basis of tlie bones of 

 higher vertebrates ; it has more resemblance to mucus ; it requires 

 1 000 times its weight of boiling water for its solution, and is neither 

 precipitated by infusion of galls, nor yields any gelatine upon eva- 

 poration. 



In like manner, the modifications of the dermal skeleton of fishes 

 have been viewed too exclusively in a retrospective relation with the 

 prevalent character of the skeleton of the invertebrate animals. 

 Doubtless it is in the lowest class of vertebrata that the examples 

 of great and exclusive development of the exo-skeleton are most 

 numerous ; but some anatomists, in their zeal to trace the serial 

 progression of animal forms, seem to have lost sight of all the verte- 

 brate instances of the bony dermal skeleton, except those presented 

 by the ganoid and placoid fishes. He must have sunk to the low 

 conception, that nature had been limited to a certain allowance of 

 the salts of lime in the formation of each animal's skeleton, who 

 could affirm, that in the higher vertebrata " the internal articulated 

 skeleton takes all the earthy matter for its consolidation (xxvii., p. 

 637), forgetting that the bulky Glyptodon, and its diminutive the 

 Armadillos, have their internal skeleton as fully developed, and as 

 completely ossified, as in any other mammals. The organizing ener- 

 gies which perfect and strengthen the osseous internal skeleton do 

 not destroy, nor in any degree diminish the tendency to calcareous 

 depositions on the surface, when the habits and sphere of life of the 

 warm-blooded quadruped require a strong defensive covering from 

 that source. 



The moment that the observations of the naturalist bring to light 

 the mode of life of any of those fishes which are said to retain an 

 unusual proportion of the external shell of the invertebrata, we are 

 in a condition to appreciate the adaptation of that external defensive 

 covering to such mode of life. The sturgeons, for example, were 

 designed to be the scavengers of the great rivers ; they swim low, 

 grovel along the bottom, feeding in shoals, on the decomposing animal 

 and vegetable substances which are hurried down with the debris of the 

 continents drained by those rapid currents : thus they are ever busied 

 re-converting the substances which, otherwise, would tend to corrupt 

 the ocean, into living organized matter. These fishes are, therefore, 

 duly weighed by a ballast of dense dermal osseous plates, not scattered 



