216 



THK EXTINCT BATRACHIA, RKI'TILTA 



the same time the splenial articulation is strongly flexed, and the inferior outline; of the 

 ramus angulate at that point. 



We have in this feature one of the most extraordinary peculiarities of this remarkable 

 genus. The mandibular arch in its usual relations enclosed a diamond-shaped area, open 

 behind, the portion anterior to the lateral angles the longer, and only closed by ligament 

 in front. The structure is an element of weakness, though indeed without such an articu- 

 lation, such a light and slender jaw would be particularly liable to fracture. There was, 

 no doubt a strong ligamentous union of the parts, as the grooved adjacent margins testify, 

 but for any supernumerary muscles to fiex the dentary bones, 1 can find no provision. 



Fiff. 51. 



A AAA 



1 Angular. 



2 Articular. 



?> Subarticular. 

 I Coronoid. 



Fitr. 52. 



Jl} Splenial. 

 7 Dentary. 



The accompanying cut shows the appearance of the normal Sexure of the ramus. The line a 5 is that which 

 exposes the section given on a. preceding page; c is the. splenial articulation; d the coronoid process, and e the quad- 

 rate cotyius. 



I am disposed to regard the structure in question as an aid to deglutition, and thai 

 when large bodies were to be swallowed whole, they passed between the rami, and were 

 accommodated by a large extensible pharyngeal cavity, and oesophagus. No doubt some 

 remarkable habit was possessed by the animals thus characterized, with which we will 

 with difficulty become acquainted. 



There is one point in which the composition of the articulation differs from that of 

 Hryx and other serpents with which I have compared it. Instead of being formed in its 

 posterior member by the subarticular hone, that, hone with a portion of the angular is 

 sheathed by one more; external, which by its position and form, appears to be tin; 

 posterior extremity of the splenial. If, as is probable from a careful study of the parts, 

 this is the case, the splenial must he regarded as a divided bone. 



The cut of the inner face of flu; right ramus, expresses the relations of these; pieces. 

 Size, 7 { nature;. 



