54 



Flacodontia — Anomodontia. 



Placodus. 



Table-case, 

 No. 17. 



and the lower jaw presents a similar strong development of the 

 coronoid pi'ocess. This powerful action of the jaws for biting 

 and grinding relates to the form and size of the teeth, which 

 resemble paving-stones, and were evidently adapted to ci-aclc 

 the shells of Mollusca, Crustacea, and perhaps Echini also, 

 upon which this reptile probably subsisted. 



The upper jaw contains a double series of these teeth, an 

 outer, or maxillary series, and an internal or palatal series ; 

 but the under jaw has only a single row of teeth. 



Although now admitted to be a reptile, this remarkable 

 genus was formerly classed by Miinster and Agassiz as one 

 of the Pycnodont fishes. 



Placodus gigas (Agassiz), A closely allied form ; ha.s a more 

 elongated cranium with a distinct premaxillary rostrum carrying 

 three chisel-like teeth on each side. It has three polygonal 



Fio. H.—Cyamndus (Placndun) laticeps (Owen), a, palatal aspect ; b, frontal aspect 

 of cranium ; frona the Muschelkalk of Baireuth, Germany. (Table-case, No. 17.) 



palatine teeth and four or five maxillary ones, 

 more elevated than in Cyamodus. 



The cranium fs 



Wall-cases, 

 Nos. 8, 9. 



Table-cases, 

 Nos. 17, 18. 



Order XI.— ANOMODONTIA. 



In this order the limbs are adapted for walking. The 

 skull is comparatively short ; the quadrate bone is fixed ; a 

 parietal foramen is present : there is one temporal arcade ; 

 the nasals are large ; in the palate the pterygoids meet 

 together in front of the basisphenoid, which they also 



