OSSEOUS SYSTEM. H5 



vary in number, and present a merely cartilaginous condition in the 

 Sirens. To these succeed the metacarpal and phalangeal bones of 

 the fingers, the latter differing in number and proportion, three in 

 a row being the usual quantity, though in the Sauria there are from 

 four to five phalanges upon some of the digits. The Ichthyic Reptilra, 

 have a few somewhat cartilaginous carpal bones. The Land Tor- 

 toises appear to have no metacarpal bones ; the phalanges are here 

 very short, but in the Marine Tortoises very long, and well de- 

 veloped to sustain the swimming paddles. In the Fw>gs, arid Sala- 

 manders, there are found from 5 7, and in the Chelonia and 

 Sauria mostly 9 10 phalanges. The two latter orders have mostly 

 five, the Batrachia four fingers. There is frequently found how- 

 ever in the males of the Tailless Batrachia, a special rudimentary 

 bone, or thumb. In the Sauria the third digit has four, the fourth 

 five joints, and both of them are very long. The Proteus and 

 Amphiuma tridactylum, as the name of the latter implies, possess 

 only three digits, while there are only two in A. didactylmn, and one 

 in Choemasaura. 



The greatest resemblance to the Mammalian type, and conse- 

 quently the most perfect condition of the bones of the Pelvis t is 

 manifested by the Sauria and Chelonia ; for it is here that we con- 

 stantly find an ilium united to the sacrum, as well as a pubis and 

 ischium, all these three bones remaining permanently separated, and 

 meeting in the acetabulum ; in both orders the ischiac unite in 

 front, like the pubic bones, thus giving rise to a symphysis; as in 

 the latter ; in the Chelonia these two symphyses approximate, so 

 as to leave an intervening obturator foramen. In the Anourous 

 Batrachia the pelvis has a V-shaped form ; the two iliac bones are 

 very long and narrow, form the branches of the letter, and coalesce 

 within such a narrow space behind with the very small pubic and 

 ischiac bones, as to leave a bony disc, perforated by the two closely 

 adjacent acetabula. In the Tailed Batrachia, and the Ichthyic 

 Reptiles (though in some of the latter, as in Siren, it is wanting), 

 the ilium is a narrower bone, united by ligament with the vertebral 

 column ; the pubis and ischium are blended together so as to form 

 a single plate of considerable size, loosely connected to that of the 

 other side, and for a great extent cartilaginous, especially in the 

 Sirens. The rudiments of the pelvis are still further diminished in 

 the Apodal Sauria, wherein a single bone is all that is invariably 

 found, situated as in many Ophidia beneath the skin, behind the 

 rib-bearing vertebrae, and nearest to the anus ; it actually supports 



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