AUTHORS ABSTRACT OF THIS PAPER ISSCEO 

 BY THE BIBLTOGRAPHIC SERVICE, DECEMBER 27 



OBSERVATIONS ON TPIE CERVICAL REGION OF THE 

 SPINE IN CHELONIANS 



R. W. SHUFELDT . 



FIVE FIGURES 



In passing in review some of the literature on the osteology 

 of the chelonians, it appears that not all of the contributors to 

 it are in full agreement with respect to the number and 

 characters of the cervical vertebrae. Intelligently to discuss 

 these differences of opinion, and the figures that have been 

 published to illustrate them, it will, first of all, be necessary 

 to define where the cervical division of the spine in a chelonian 

 begins and terminates. As to its beginning, there is no question, 

 for the first vertebra of the chain is the atlas, as in all the Verte- 

 brata, and it articulates with the occipital bone of the cranium 

 by a single, median condyle. 



Giinther ('86, pp. 445 and 449) very clearly expresses his views 

 on this subject. In defining the order Chelonia, he states: 

 "Cervical and dorsal vertebrae not numerous. The dorsal 

 vertebrae and expanded ribs (with the exception of Sphargis) 

 are united into a carapace, the elements of which are immovable, 

 and which is completed ventrally by a number of dermal bones, 

 a true sternum being absent and replaced by a plastron." Ac- 

 cording to this very clear statement, the anterior dorsal vertebra 

 is the first immovable one, which, by the aid of its pair of ribs, 

 enters into the formation of the extreme forepart of the carapace. 

 All the vertebrae between this one and the skull are free and 

 ribless, and together constitute the true cervical vertebrae. 

 Further on in this article (p. 449), referring to the spinal column 

 in the Chelonia, he says: "There are always 8 cervical, 12 dorsal, 

 and 2 sacral vertebrae." According to this, then, it is very 

 definitely fixed as to which vertebrae are to be considered cervicals 

 and which dorsals, and the exact number of each division of the 

 spine in all existing chelonians. 



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