Dr. G. Baiir on Meiolauia. 



43 



supported by the intercentrum. The conditions of the cen- 

 trum of the athas in the Testudinata may be ex[)rcs.sed in the 

 followina: diaoraui, in which the centrum is seen from 

 above : — 



Crvptodira : no face for ueuroids. 



Podocnemididas : a small face for neuroids. 



Chefvdidre, part, Chclyim/s (for ex.) : a larger face for neuroids 



Chelvdidte, part (Steruothaeridoe) : a large face for neuroids. 



Tlie conditions of the first two vertebrae in the Cryptodira 

 and Pleuvodira could be expressed also in the following- 

 way : — In the Cryjitodira the atlas-ring has a free articulation 

 with the atlas-centrum ; in tiie Pleurodira the associated 

 neuroids and the atlas-centrum have a free articulation with 

 the centrum of the axis. 



10. " With regard to Miolania, I can state that the neuroids 

 of the atlas are supported by both the liypapophysis (first 

 intercentrum) and the centrum, that the latter articulated 

 freely with the second centrum, and that the diapopliyses of 

 the second vertebra are not partly below the praizygapophyses, 

 as in all Cryptodira, but entirely beliind ; in all these respects 

 agreeing with the vertebrjB of Podocnemis madagascariensis 

 figured above." 



In regard to tliis I state that after a careful comparison of 

 the atlas of Meiolania with other specimens I am convinced 

 that the neuroids are exactly in the same connexion as in the 

 -Cryptodira, especially the Testudinida3. They stand entirely 

 on the first intercentrum, with which they are coossified; 

 there is no articular face on the top of the atlas-centrum for 

 the neuroids. Whether the atlas-centrum articulated freely 

 or not is impossible to determine in the specimen, but it is 

 very doubtful that it did articulate freely. 



The diapophysis of the axis is a trifie behind the prajzyga- 

 pophysis in iJeiolama ; we have the same, if I remember 

 rightly, in Staurotypus ; if the diapophysis of Testudo poly- 

 phemus should become more slender, we would have the same 

 arrangement ; the thick basis of the diapophysis woukl be 

 used up for this, and the diapophysis would be behind the 

 zygajjophysis. But this difference is of no importance. lit 



