THE HATRACllIA OF NOliTH AMERICA. 



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extinct onlcrsot' Uatnicliia are not th« centra of the higher vertebrata, 

 but are intercentra, w hidi are occasionally seen in the higher vertebrates 

 in a rudiniental condition. This is especially the case in the remark- 

 able saurian of New Zealand, the Si)henodon, and in the extinct order 

 of the Theroniora. Owen has shown that the mtcrcentra exist also in 

 the mole. I have given the following reasons for this view: 



1. The intercentra are very large in the Ganocephala and KhacUi- 

 tonii. 



, They support the neural arch in the Enibolomeri. 



J. They are not rndimental in existing Batrachia. 



4. The chevron bones, which originate from the intercentra of Kep- 

 tilia, are continua with the caudal vertebral bodies in Iiatrachia, 



.J. Tlie ribs, which originate from the intercentral cartilages in Kep 

 tilia, originate from the vertebral bodies of Batrachia. 



Tiie paleontology of the Batrachia and Beptilia shows that the order 

 Enibolomeri is tlie only one with complete vertebral bodies, and so 

 probably gave origin to the reptiles; while the intercentra in some 

 Batrachians become so connected with the neural arches as to lead to the 

 belief that they become the vertebral bodies of later forms of the class 

 whii'h JMve <lescended from them. 



In a'- the orders, genera with well-developed antericu' limbs display 

 well-developed distal condyles of the liumeru: . They are better de- 

 veloped than ill any order of reptiles, with the exception of the Thero- 

 niora. 



With regard to the cranial nerves, it is to be remarked that the latera- 

 lis brancii of the vagus is present, as in fisiies; also that the glossopha- 

 ryngeal is united with tlie vagus. In the Urodehi the nervus facialis is 

 distinct from the trigeminus (Fig. 1), but in the Salientia they are 

 united. (Plate 4.S.) 



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FUi. 1. Dia-iraii ui olKHulrooraiiiuiii ami cranial nerri's of Salainaii.lra, side ^iew (from 'Wiedersheim). 



In the museular system the Batrachia diifer from the fishes in the 

 niodifu'atious which partially take the place of the myocommata, and 

 the development of the muscles of the limbs and their extension on 

 the dorsal and vei tral surfaces of the body. Myocommata persist in 



