152 On a new Chelonian. 
zygapophysis is broken away. These vertebra seem to agree 
very well with those of Glyptops described by Hay (‘ Fossil 
Turtles of North America,’ p. 49). 
The dimensions of the more complete of the two cervical 
vertebree are :—Length of centrum 13°5 mm., width of poste- 
rior articular surface § mm., width between ends of transverse 
processes 17 mm. 
There seems to be no doubt that the turtle above described 
should be referred to the group Amphichelydia, as defined 
~by Lydekker and Baur; the absence of fusion of the pelvic 
bones with the xiphiplastra, the concavity of the anterior 
border of the nuchal bone, and the presence of amphiccelous 
cervical vertebrae separate it from the Pleurodira. The 
absence of mesoplastra is unusual in the Amphichelydia, but 
occurs in the Plesiochelyide, a family which Hay and others 
refer to that group. 
In its general form this specimen is very similar to the 
turtle described and figured by Riitimeyer * as Plestochelys 
jaccardi, but in details of structure there are considerable 
differences—e. g., in the form of the vertebral shields,—which 
in the present specimen diminish in size from the second to 
the fourth, while in Riitimeyer’s specimen the second and 
fourth are larger than the third. The form of the anterior 
lobe of the plastron is also very different. 
_ The specimen described and figured by Riitimeyer as 
Plesiochelys jaccardi differs in several respects from the original 
Emys jaccardi of Pictet +, and is probably really a different 
species. Pictet’s species differs considerably from our speci-~ 
men in (1) the much greater width of the vertebral shields, 
(2) in the form of the anterior lobe of the plastron and parti- 
cularly of the entoplastral bone. I regard our specimen as 
specifically distinct from both MRiitimeyer’s and Pictet’s 
specimens. As to its generic reference, there is considerable 
difficulty. Riitimeyer, in his definition of the genus Plesio- 
chelys, states that the pelvis is united with the plastron, and 
although, so far as I can find, he gives no figure or description 
of such a union in the case of the type-specics P. solodurensis, 
he does figure the posterior part of a plastron of P. etalloni in 
which such a union took place (op. cit. pl. viii. fig. 8). Since 
in our specimen the contact of the pubis with the xiphi- 
plastron is only indicated by an obscure facet, it seems 
* “Die fossilen Schildkr6ten von Solothurn,” Neue Denksch. Schweiz. 
naturg. Gesellsch. Bd. xxv. (1878) pls. ii. and iii. 
+ “Reptiles et Poissons du Jura Neuchatelois,” Matériaux pour la 
Paléontologie Suisse, sér. iii. 1, p. 15, pls, i,-iii. 
