564 PROF. OWEN ON THE ENDOTHIODONT REPTILIA. 
and batrachial dental character cropping up, so to speak, in excep- 
tional cases of Reptilia, rising toward the establishment of the 
crocodilian type, above which group of advanced Reptilia calcified 
palatal teeth no longer appear in the vertebrate series. 
EXPLANATION OF PLATE XXVII. 
Fig. 1. Section of part of right mandibular ramus, exposing the three rows of 
teeth, Endothiodon bathystoma. 
2. Side view of fore part of skull, Endothiodon uniseries. 
3. Under view of the same. 
4. Upper view of the same (one half nat. size). 
5. Front view of the same (2.). 
(All the other figures are of the natural size.) 
Discusston. 
Prof. SreLry inquired whether Prof. Owen had examined into the 
resemblances between Hndothiodon and those European Muschelkalk 
reptiles which form the genus Placodus. The superficial resem- 
blance was the more suggestive since animals closely allied to the 
South-African Anomodonts had already been described from Per- 
mian rocks in Russia. He also inquired as to the nature of the cra- 
nial characters which led the author to class the Endothiodont group 
rather with the Anomodonts than with those animals which Prof. 
Owen had called Theriodontia. 
Prof. Owrn replied that the great point of distinction between the 
Theriodontia and Anomodontia was that in the former the teeth are 
developed on the alveolar border of the jaws, not on the palate. In 
Endothiodon the teeth are palatal, and, as in Oudenodon, there are 
no teeth on the margin of the upper jaw. Other secondary points 
of distinction also go with these. 
