20 THE OSTEOLOGY OF THE REPTILES 



riorly in the Squamata (Figs. 55 c, 56 b) they articulate with the 

 palatines only, as also in some Chelonia (Figs. 31 a, 32 b) and 

 Plesiosauria (Fig. 46 b). Generally believed not to represent the un- 

 paired vomer of the mammals. 



Palatines {pi). Primitively (Figs. 6, 21) forming the posterior 

 boundary of the internal nares, articulating with the prevomers and 

 pterygoids on their inner sides, the maxillae on their outer, and with 

 the descending process of the prefrontals above. More or less denti- 

 gerous. 



Fig. 6. Pantylus. Cotylosaur skull: from below. 

 Three fourths natural size. 



Teeth are still present in the Theromorpha (Figs. 40 c, 42 c) and 

 some Therapsida, but are lost in other reptiles except the Rhyn- 

 chocephaha (Figs. 62 e, 63 b) and most Squamata (Fig. 54 b). They 

 may join in the middle in the Chelonia (Figs. 31 b, 32 b) and in the 

 Crocodilia (Fig. 69 b) below the prevomers. 



Pterygoids (pt). (Figs. 6, 7, 21, 40 c.) Bones of the posterior part 

 of the palate, articulating with the prevomers in front, the palatines 

 and ectopterygoids laterally, the basisphenoids on the inner sides, 

 the quadrates and squamosals posteriorly. Dentigerous. 



As stated above they do not articulate with the prevomers an- 

 teriorly in the Squamata and many Chelonia and Plesiosauria, but 

 do articulate with the parietals in many Chelonia. Their connection 



