104 BAKON F. NOPCSA ON THE PRIMITIVE EEPTILIA [vol. lxxix, 



(A) Kallokibotion bajazidi, gen. et sp. nov. 



This new genus is represented by several specimens ; with the 

 exception of a few, they are preserved in the British Museum 

 (Natural History). In one the plastron and the nearly entire 

 impression of the carapace, as well as a natural cast of the body- 

 cavity, are splendidly preserved. A second individual shows the 

 disintegrated and somewhat crushed carapace, parts of the plastron, 

 and a fairly well-preserved skull. A third shows a well-preserved 

 but laterally somewhat crushed carapace from above, the entire 

 pelvic girdle, the cervical and caudal vertebrae, and some limb- 

 bones. Yet another specimen has a badly-preserved skull, isolated 

 cervical land caudal vertebrae, limb-bones, and shows the dorsal 

 vertebrae from the interior. Other specimens of minor importance 

 show parts of the scapular arch, limb-bones, parts of the pelvis, 

 and so on. It is evident that practically the whole of the skeleton 

 is known ; but, since the detailed description is to be published 

 elsewhere, 1 only the principal traits of this interesting genus will 

 be mentioned here. The skull is completely roofed over like in 

 Baena sima (BO). The cervical vertebrae show strong lateral 

 processes, and resemble in outline those of Chisternon hebraicum 

 (30) ; they are, however, deeply biconcave in all specimens. The 

 caudal vertebra; are strong and biplane, and show that the tail was 

 well-developed. The carapace shows well-developed neural bones 

 and vertebrae, very broad dorsal scutes, small costal and marginal 

 scutes, but no supernumerary scutes such as occur in Baena, 

 Thescelus, Soremys, Platychelys, and other primitive tortoises 

 (30). The posterior margin of the carapace is moderately scal- 

 loped ; on the plastron one can distinguish a well-developed nieso- 

 plastron reaching to the middle line of the body, and several 

 inguinal scutes. In the interior may be discerned on the carapace 

 two marked tuberosities for the attachment of the superior ends of 

 the scapulae, and on the plastron tuberosities for the attachment 

 of the pubes and ischia. Scapula, proscapular process, and coracoids 

 are all rod-like ; the glenoidal fossa is well marked and very deep ; 

 the prepubic process is ossified, as in Chisternon hebraicum (30) 

 and Orlitsia ; the ischia unite by a broad and deep symphysis 

 which forms a vertical wall, showing in the middle a convexity 

 directed forward, aiid resemble thus the ischia of Orlitsia. The 

 femur and humerus are dilated at both ends, and show remark- 

 ably well-defined and smooth surfaces for articulation. The toes 

 ended in well-developed claws. 



The nearest European relatives of Kail okibot ion seem to be 

 Plesiochelys and Pleurosternon, which are abundant in the 

 "Wealden Beds (2, 48, 78). Among the American Amphichelydae, 

 only Glyptops is known to possess biconcave vertebrae ; and this 

 genus, although lasting perhaps until the end of the Cretaceous 

 Period, shows a maximum of development in the Niobrara phase (30). 



1 P. Nopcsa, ' Kallokibotion, a Primitive Amprnchelydean Tortoise ' Palae- 

 ontologia Hungarica, vol. i, Budapest, 1923 (in the press). 



