Dr. G. Baur on Meiolania. 43 
supported by the intercentrum. The conditions of the cen- 
trum of the atlas in the Testudinata may be expressed in the 
following diagram, in which the centrum is seen from 
above :— 
1 2 
1. Cryptodira: no face for neuroids. 
2. Podocnemididee : a small face for neuroids. 
5. Chelydide, part, Chelymys (for ex.): a larger face for neuroids, - 
4, Chelydide, part (Sternotheeridz) : a large face for neuroids. 
The conditions of the first two vertebra in the Cryptodira 
and Pleurodira could be expressed also in the following 
way :—In the Cryptodira the atlas-ring has a free articulation 
with the atlas-centrum; in the 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 hypapophysis (tirst 
intercentrum) and the centrum, that the latter articulated 
freely with the second centrum, and that the diapophyses of 
the second vertebra are not partly below the prezygapophyses, 
as in all Cryptodira, but entirely behind ; in all these respects 
agreeing with the vertebrae of Podocnemis madagascariensis 
figured above.” 
In regard to this I state that after a careful comparison of 
the atlas of M/ezolania with other specimens I am convinced 
that the neuroids are exactly in the same connexion as in the 
Cryptodira, especially the Testudinide. 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 trifle behind the prazyga- 
pophysis in Mevolania; 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 would be 
used up for this, and the diapophysis would be behind the 
zygapophysis. But this difference is of no importance. Jn 
