Baur, Morphogenie der Wirbelsule der Amnioten. 339 



the anterior dorsal region of some Lacertilia; and as the chevron 

 bonos of most reptiles and some mammals." 



Nun folgt die erste Arbeit von A. Gaudry 1 ). 



p. 5 (Separatabdruck) sagt Gaudry ber Actinodon (Batrach.) 

 Le centrum est compose de trois os. L'os inferieur est le plus ira- 

 portant." (Conf. Nouv. Arch. Mus. Hist. Nat. t. III. 1867.) 



p. 7. Les os lateraux du centrum, qu'on peut appeler pleuro- 

 centrum pour les distinguer de l'os inferieur. . . ." 



Am 5. Juni 1880 erschien Cope's zweiter Beitrag ber die Verte- 

 braten der Permformation von Texas 2 ). 



Er stellt Archegosaurus , Actinodon, Trimerorhachis , Ehachitomus 

 und Eryops zu den Ganocephala Owen, welche er folgendermaen 

 charakterisiert: p. 14. 



Vertebrae consisting of centra and intercentra, the former not 

 extending to the base of the vertebra, the latter not rising to the 

 neural canal. The centrum consisting of two parts distinct from the 

 superior neural arch; viz., a lateral piece (pleurocentrum) , on each 

 side. Atlas consisting of separate segments, the superior of which 

 are not united above the neural canal, and the inferior (intercentrum) 

 divided on the middle line, into two Segments." 



Von Eryops sagt Cope p. 14: The largest dement of the ver- 

 tebra is the intercentrum which occupies the entire inferior sur- 

 face of the vertebra. The element representative of the centrum is 

 wedged in between the superior external angles of adjacent inter- 

 centra, as in Trimerorhachis. " 



Von diesem p. 18: The portion of the atlas which represents 

 the intercentrum is divided into two lateral portions, each of which 

 has the form of an entire intercentrum, i. e., crescentic. The inter- 

 centrum of a cervical of a large species of this group, is wider than 

 that of the other vertebrae, and presents two articular facets anteriorly." 



Wir werden spter sehen, dass diese Verhltnisse von sehr groer 

 Wichtigkeit sind. 



Im April 1882 schuf Cope 3 ) die Subordnung Rhachitomi fr 

 Trimerorhachis, Eryops, Actinodon, Zatrachis\ da F ritsch angegeben 

 hatte, die Wirbel von Archegosaurus wren nicht segmentiert. 



1883 beschrieb Gaudry 4 ) die Wirbel von Enchirosaurus und 

 gab dem Intercentrum" Cope den Namen Hypo centrum. 



1) Gaudry A., Les reptiles de l'epoque perrnienne aus environs d'Autun. 

 Bullet. Soc. g6ol. France 3e ser. t. VII. sance du 16. Decenibre 1878. 



2) Cope E. D., Second contribution to the history of the Vertebrata of 

 the Perarian Formation of Texas. (Read bef. the American Philos. Soc. May 7. 

 1880. Pal. Bull. Nr. 32.) 



3) Cope E. D., The Rhachitoinous Stegocephali. Am. Nat. April 1882. 

 p. 335. 



4) Gaudry A., Les enchainements du Monde animal dans les temps go- 



logiques. Fossiles Primaires. Paris 1883. p. 273. 



22* 



