TELEOLOGY OF THE SKELETON OF FISHES. 14-9 



by the hypothesis of transmuted Crustacea. Some have gone so far 

 as to affirm, that in all those solid parts that cover and shield the 

 exterior of the body of the sturgeon and analogous fishes, " there is 

 nothing in the least analogous to any part of the internal articulated 

 skeleton of Vertebrata," but that " it is entirely a remnant of the 

 superficial shells of In vertebrata." (xxvii. p. 337.) You would 

 hardly suppose from these exaggerated expressions, that both ganoid 

 and placoid plates are as richly organised and permeated by nutrient 

 vessels as the bones within ; and that they present the same micro- 

 scopic structure as the ossified parts of the endo-skeleton, which they 

 serve to protect. I have proved this with regard to the existing 

 Lepidosteus, and the extinct Lepidotiis. (v. p. 14.) Drs. Peters 

 and MuUer have shown the osseous rayed corpuscles in the scales of 

 Polypterus and other Ganoids. Nay, many of the ganoid fishes have 

 these modified bony scales articulated in regular series by a kind of 

 gomphosis, like the pegs and sockets by which the tiles of a roof are 

 linked together. The dermal bones which form the carapace of the 

 Armadillo have the same cellulo-reticulate interior structure as the 

 carpal, tarsal, or other bones of the endo-skeleton not excavated by 

 a medullary cavity. This is well demonstrated in the dermal bones 

 of the great extinct Glyptodons. * 



The great proportion of the primitive cartilage which is retained 

 in the skull of many of the Osseous Fishes, the Salmon and Pike, for 

 example, and the greater proportion of the animal to the earthy 

 matter in all the bones, their coarse texture, the radiating fibres of 

 the flat cranial bones, and the general absence of dentated sutures, 

 are all persistent characters in Osseous Fishes, which remind the An- 

 thropotomist of transitional ones in the human foetus ; but the light 

 of teleology demonstrates the perfection of such, so termed embryonic, 

 conditions, in relation to the atmosphere and movements of the Fish. 

 It is generally in fresh-water abdominal Fishes that the semi-osseous 

 condition of the skull is found, and the diminution of the quantity of 

 heavy earthy particles may be connected with the less dense quality 

 of their medium, as compared with sea-water, and with the usually 

 more posterior position of the ventral fins. 



In reference to the analogies to the form of a fish, avc nuiy be re- 

 minded that the head of the human embryo is disproportionately large. 

 True : but the head of a fish must needs be large to meet and over- 

 come the resistance of the fluid, in the mode most favourable for rapid 

 progression : it must therefore grow with tiie growth of the fish. 



• M. de Blainville, in tlie " Generalites Osteologiques," prefixed to his great 

 •' Osteographie," admits that the structure of the dermal bones has a certjin re- 

 seml)laiice with tliat oF true hones; but errs in stating, " avcc cette difTcrenec 

 importante, qu'cUe n'est jamais cellulcuse et reticulde." 4to. 1839, p. 12. 



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