SQUAMATA 



155 



A single series of large conical teeth occurs in both ujaper and lower jaws, 

 those of the pterygoid being inferior to the rest in size. The crown often 

 exhibits slight anterior and posterior carinae, and may be bevelled into several 

 longitudinal facettes ; and the enamelled surface may be either smooth or 



Fig. -lib. 



Mosasauriis camperi, v. Meyer. A, Outer; and B, Inner 

 aspect, 1/4. (aZ, Suprastapedial process ; k, Stapedial pit ; 

 I, Meatus ; m, Superior margin ; 11, Inferior margin), (after 

 Owen.) 



Fio. 246. 



Clidastes propython, Cope. 

 Quadrate, inner aspect, 2/3. 

 (Lettering as in Fig. 245), 

 (after Cope). 



delicately striated. All the teeth are fixed by tumid osseous bases in shallow 

 pits of the supporting bone. Successional teeth arise alongside the functional 

 ones, and gradually displace them by pressure against the crown on the inner 

 side. 



The pectoral arch (Fig. 247) exhibits a rather large and flattened coracoid, 

 the articular border of which is thickened and divided into two facettes 



Clidcistes velox, Marsh. Pectoral arcli, dorsal aspect, i/g. (o, Coracoid ; h, Humerus ; iiu\ Metacarpus ; 

 r, Radius ; sc, Scapula ; u, Ulna ; I-V, bigits), (after Marsh). 



meeting at an obtuse angle, while the thin inner edge is rounded, and often 

 incised by a deep notch or emargination. There is a small coracoid foramen 

 situated toward the articular border. Posteriorly the coracoids meet the 

 sternum, which was probably never ossified, but composed of calcified cartilage, 

 quite like the sternal ribs. The coracoids are separated from each other by a 

 broad epicoracoidal expanse of cartilage. The scapula is placed as in Rhyn- 

 chocephalians ; a slender interclavicle (episternum) is present, but clavicles are 



