niSTOKY OF THE WORKS OF CUVIER. 157 



tlie clavicle, lias always three in the bird: the scapula or omoplatc, the clavicle, 

 and the coracoid bone; it has only two in the crocodile, the scapula, and the 

 coracoid, the true clavicle being wanting- ; the three bones reappear in tlie lizards ; 

 there are two in the tortoise, the scapula and coracoid, or perha])S three, for there 

 are traces of a clavicle ; there are certainly four in the frog, the clavicle, coracoid, 

 and an omoplate, divided into two pieces; and, what is remarkable, it is precisely 

 of these two pieces of the omoplate that the shoulder of fishes is composed. Tho 

 sternum in the crocodile is a single 1)one; in the tortoise it is always composed 

 t>f nine pieces ; it recovers in the lizard the simplicity which it exhibits in the croco- 

 dile ; it has but two ossified pieces in the frog; a sort of sternum is hardly dis- 

 coveralde in certain fishes; in the mammals, on tho contrary, it is highly developed; 

 here we count as many as seven, eight, nine pieces, placed ordinarily on a single 

 line; and as to birds, there are five pieces in the gallinacea; there are not more 

 than two in ducks ; its composition is again changed in pigeons, in sparrows, in 

 birds of prey, &c. Thus the sternum not only varies from one class to another, 

 it varies in the same class, and that in the very class of birds where, in general, 

 unity or conformity of organization is so constant and conspicuous. 



But, in reference to this question of osteological unity in vertebrate animals, 

 there are two apparatus which have a peculiar importance : these are the aurkuJar 

 and the Injokl apparatus. By tho auricular apparatus we here designate a chain 

 of small bones, placed within the tympanum of the ear, and which extends from 

 its membrane to the fenestra ovcdis. In the mammals we count ahvays four 

 of these small bones, the malleus, the incus, the lenticular, and the stapes; in 

 the birds we find but one, fonned of two branches, one of which adheres to the 

 tympanum, the other presses upon the fenestra oralis; in like m.anner a single 

 ossicle replaces, in the crocodile, the four small bones of the ear of mammals ; it 

 is a stapes still more simple than that of birds; * there is but a single ossicle in 

 the tortoise, the lizard, the serpent ; in the frog, the auricular chain might be pro- 

 nounced somewhat complex did it not remain in great part cartilaginous ; lastly, 

 in the salamanders, the sirens, the protei, the last auditory ossicle itself, the 

 stapes, is reduced to a simple cartilaginous plate. From this to the complex 

 apparatus of the mammals is certainly a wide interval, and when we thus follow 

 step by step this successive simplification, when we arrive thus at that final 

 reduction of the whole apparatus to a simi)le cartilaginous plate, we recognize 

 the full force of j\[. Cuviei-'s opinion that this apparatus, after having disappeared 

 in the aerial verteV)vates, is not all at once restored in the class of fishes, there to 

 form the opercuhi, and that these opercula are conserpiently a special apparatus 

 appropriate to this latter class. 



The facts which concern the inverse progression of the hi/oid npparatus, that is 

 to say, its gradual development from the mammals to fishes, are still more import- 

 ant, and, in relation to theories of the skeleton, more decisive. In man this appa- 

 ratus is composed of five parts : of a l)ody, of two branches or anterior processes 

 "which suspend the hyoid to the cranium, and of two posterior ones which suspend 

 the larynx to the hyoid. Even in the mammals the apparatus undergoes great 

 modifications, depending on the form of its body, the soldering of this to the pos- 

 terior branches more or less promptly, the number, shape, and proportion of the 

 anterior branches. In birds these anterior branches are no longer attached to 

 the craniinn,'but simpl}' pass around and behind it ; to the back j)art of the body 

 of the l)Oiie is soldered a single slender ])one, on which rests the larynx, and 

 which, in itself alone, represents the two posterior branches; in front is another 

 bon<^ which penetrates into the tongue, l/cing thelinguul l)one. 



The h/joid of the crocodile is one of the most simple. Its body consists of a 



* We. iiiig^ht, in truth, give the name of malleus to that brnuch which in birds and croco- 

 diles is inserted in the membrane of the tympanum, but still there would be neither incus nor 

 lenticular ossicle. 



