1 198 CLASS REPTILIA. 



the nares are similarly approximated to the orbits, with the inter- 

 vention of a preorbital vacuity, which (fig. 1096) may be very 

 large ; while the occipital condyle is situated on the base of the 

 cranium ; and the orbits are large, and there is generally an ossified 

 ring in the sclerotic. The teeth are invariably simple and pointed ; 

 and are always implanted in separate sockets. In the pectoral 

 girdle the scapula and coracoid are long and bird-like, and the latter 

 has no fontanelle ; there were no clavicles ; but there was a broad 

 heart-shaped sternum (fig. 1095, b), carrying a median keel superi- 

 orly. The angle of junction of the scapula and coracoid, as well 

 as the keeled sternum, curiously resemble the corresponding parts 

 in the skeleton of the Carinate Birds, and are consequently totally 

 unlike those of the Ratitse. The carpus consists of two main bones, 

 one distal and the other proximal ; x while on its radial side there is 

 a small styliform ossification, regarded by Professors Owen and 

 Marsh as the representative of the pollex — an identification which, 

 if correct, will make the four remaining digits which are usually 

 present the 2d, 3d, 4th, and 5th of the typical series, and not the 

 1 st, 2d, 3d, and 4th as they are regarded by some writers (fig. 

 1095). The phalangeals of the ulnar digit, as already mentioned, 

 are enormously elongated, and the terminal joint has no claw. 

 The pelvis is relatively weak ; and although the ilium is extended 

 on both sides of the acetabulum, the structure of both this region 

 and of the pelvic limbs is far removed from the avian type. 

 Thus the pubis (or prepubis) is directed forwards, and the ischium 

 is short and wide ; while the pelvic limbs are relatively short. The 

 fibula is, however, always fused with the tibia ; and the astragalus 

 may also unite with the latter bone ; although the metatarsals always 

 remain distinct both from one another, and also from the distal 

 row of the tarsus. The greater number of the bones are hollow, 

 and are frequently provided with pneumatic foramina, like those of 

 Birds. The brain was bird-like, and the body was probably naked. 

 In time this order ranges from the Lias to the Upper Chalk ; and 

 was especially abundant in the Upper Jurassic and Cretaceous 

 strata of both the Old and New Worlds. Although the skeleton 

 presents many remarkable resemblances to the Carinate Birds, yet 

 these must be regarded as mainly due to adaptation for a similar 

 mode of life ; since it seems clear that the Pterodactyles are 

 altogether off the direct line of the Avian pedigree. 



Suborder i. Pteranodontia. — In this suborder teeth are 

 totally wanting, and the jaws were probably completely ensheathed 

 in horn, like those of Birds. The skull (fig. 1096) has an enormous 

 supraoccipital crest, projecting far behind the occiput ; and the nares 



1 The carpus is erroneous in fig. 1095. 



