S1HKX. 



SlllKV. 



the end of tho lu-ls, under the namo of Munrna Sinn. These 

 differences of n; inimi stiflieii-nUy show tho doubta which arose on the 

 examination of this extraordinary form. 



Cuvier in 1S07 satisfactorily established, in a memoir read to the 

 Inittituto of Franco, and inserted in the first volume of the 'Zoolo- 

 gical Observations of Hutnboldt,' that whatever changes it might 

 undergo, the Siren was a reptile mii generis, which never could have 

 hiinl feet, and whose whole bony framework differed esscntittlly from 

 that of the Salamanders ; that there was DO probability that it ever 

 changed its form or lost it* branchiae ; and that tho Siren is conse- 

 quently a true Amphibian, which respires at will throughout its life, 

 eitl.cr in the water by means of branchuc, or in the air by means of 

 lungs. This conclusion rested upon that solid basis which has given 

 Mich value a value daily becoming more appreciated to the views 

 of this great zoologist his personal observations made on tho osteology 

 and tplHiichnology of tho animal. 



That the Siren is a perfect animal belonging to the Pcrennibranchiato 

 Batrachians is now admitted by all zoologists. Cuvier indeed remarks 

 (' Regne Animal '), that the branchiic of Sinn intermedia, and ,S'. iiiinta 

 have been regarded as not participating iu their respiration, and 

 that iu consequence Dr. J. E. Gray has formed them into the genus 

 J'ttudvl/ranchus. Cuvier however adds that it is nevertheless not 

 difficult to see on their lower surface folds and a vascular apparatus, 

 the use of which does not appear doubtful to him ; and that M. Leconte 

 has satisfactorily demonstrated that both these species, as well as Sirett 

 laccrtina, are perfect animals. 



Cuvier remarks that the Siren should be judged of not after 

 Amfliiuma, but from itself. He accordingly procured some Sirens, 

 and saw an osteology so finished and so firm, that it was impossible 

 to believe that they were not adult The branuhite of these individuals 

 were perfectly entire, and their lungs completely developed, and rich 

 in well-filled vessels. No doubt therefore existed in his mind that the 

 animals used both. 



The simultaneous existence, he observes, of a larynx and a trachea 

 with a branchial apparatus not only permanent, but perfectly ossified 

 in many of its parts, is also worthy of especial attention, aud proves, 

 as is evident in the frogs and salamanders, that the branchial ap; 

 is no other than a more complicated os hyoides, and not a combination 

 of pieces proceeding from the sternum and larynx. He adds, that it 

 is to the Salamanders that the Sirens approach most nearly by the 

 structure of the head, although neither the general form nor the 

 proportions of the parts have so near similarity. 



The skull of tho Siren is narrowed iu front by reason of the exces- 

 sive reduction of the maxillary bones, which consist only of a very 

 small osseous point. Behind there is a strong occipital crest on tho 

 parietal and petrous bones. The pieces which form the lower jaw, 

 instead of being transverse like the bronchus of a cross, are directed 

 obliquely forwards. The parietal bones occupy the greatest portion 

 of the upper part of the cranium. They hove each in front a point, 

 expanding so as to lodge between them the posterior part of the 

 priucipal frontal bones, which have each a groove for the lodgment of 

 the posterior point of two p lender bones, which proceed beside each 

 other to the end of tho muzzle. At their sides are attached two other 

 bone*, which arc slender and pointed backwards, and which descend 

 and widen far in order to raise the anterior edge of the jaw. Cuvier 

 takes the first for the nasal bones, and the others for intermaxillary 

 bones. These last are tootblc-x, but their edge is trenchant, and fur- 

 tiii-lied, when the animal is alive or well preserved, HI well as the edges 

 of the lower jaw, with a sheath which is nearly horny, is easily 

 detached from the gum, aud has its analogue iu tho tadpoles of (ho 

 frogs. All the lower part of thu cranium and the face is composed of 

 a large and wide sphenoid, which extends from the occipital hole to 

 the inU-rmaxillarie.". The sides of the cranium, in the orbital. r.-gioii 

 and the front of the tempmnl bone, are cloicd by a single bone, iu 

 which are pierced, forward, the olfactory aperture ; farther back, the 

 optic hole, and auother for the first branch of tho fifth pair, and 

 probably for the small nerves of the eye. To the palate, under tho 

 anterior and lateral part of the sphenoid aud orbital bones, are fitted 

 two delicate plates beset with hooked teeth. 



The lower jaw of tho Siren U composed of four bones on each side ; 

 one of which forms the syuiphysis and the trenchant border of the 

 jaw, which it invests externally up to n ar its posterior extremity. 

 The whole of this bone is bese.t with small pointed teeth disposed 

 cjuincuncially like those of the palatal j. 



The on hyoidi of the Siren is nn os hyiidca of the larva of a 

 Salamander or of the Axolotl, but very much ossified in many of its 

 part* 



-hniiMcr-hl.vlc of the Siren is slender, nearly cylindrical, mr- 

 : in it* middle, and augmented on ths spinal xidu by a cartilagiuou 

 ;. Thu clavicle and the curacoid are ivpre-eiitcd by two cartila- 

 ginous lobes, ono directed forward*, tho other much wider, proceeding 

 upon the breast and crossing upon that of tho opposite side. In the 

 external border of this coracoid cartilage, near and a little behind tin; 

 articular fossa, is a bony ncniilunnr lamina, which is the sole repre- 

 sentative of the bony coracoid ; but tlnro is nothing similar for the 

 clavicle. The huincrui, compressed laterally above, from before back- 

 ward* below, and narrowed in iu middle, has iu extremities cartila- 

 ginous. It is the same with the two bones of the fore arm, both rather 



slender, and the internal bone or radius widened below. The bones 

 of the carpus remain cartilaginous. 



Each of the four fingers has a metacarpiau, aud two phalanges only. 



Anterior portion of the skeleton of Sirtn laecrtina, n, dors.il vcrtibra s-ccn 

 behind ; b, the same ecen before. 



There is no vestige of a pclvi*, nor of any posterior extremity, 

 either osseous or cartilaginous. 



Cuvier did not find iu a large individual more than 43 vertebrae in 

 the trunk and 44 in the tail : but the individual which he described 

 in 1807 had three more. 



In the vertebra) which carry the ribs, the upper lamina of the 

 transverse apophysis is but little marked, and the point is stout and 

 divided into two lobes for the two tubercles of the rib, as in the 

 salamanders. Cuvier only found eight of these vestiges of ribs on each 

 side, commencing from the second vertebra. The two lost have the 

 head simple. At the tail, the transverse apophyses, which have already 



Klltire skeleton of Siren lac, I'lina. 



become rather small, promptly disappear; the articular apopbyses 

 iliminiih also by degrees. The body of the vertebra takes a very 

 compressed form, aud gives below two small lamina;, which intercept 

 a canal for the vessels, like th chevron bones in the lizards. 



