ORDER DINOSAURIA. 1 165 



make a nearer approximation than the Sauropoda to the general- 

 ised Crocodilia, although in their hollow limb-bones they agree 

 with the higher Ornithopoda. All the forms were carnivorous. 

 In the skull (fig. 1070) the premaxillse are fur- 

 nished throughout with teeth, which are laterally 

 compressed (fig. 1065) and backwardly curved, 

 with trenchant edges, of which the posterior, and 

 frequently also the anterior, border is serrated ; 

 the directions of these serrations being generally 

 nearly at right angles to the axis of the crown. 

 These teeth are always implanted in distinct p . io6 _ Lateral 

 sockets ; and the skull has a large preorbital va- aspect of a tooth of 

 cuity (fig. 1070). The centra of all the vertebrae lafdiT^'from The 

 are hollowed internally; and their neural arches QnT-S nfturai 



size. 



articulate by zygosphenes (diplosphenes) corre- 

 sponding to those of the Squamata; while the 

 centra (fig. 1067) are much compressed laterally. The limb-bones 

 always have medullary cavities ; and since the pectoral limb is much 

 shorter than the pelvic, it is probable that many forms were of 

 bipedal habits, although some may have been quadrupedal. In 

 the pelvis (fig. 1064) the ilium is of great vertical depth, and has a 

 short preacetabular process : while the pubis is directed downwards 

 and forwards, and unites with its fellow in a long bony symphysis, 

 which is generally extended up the anterior face of the two bones ; 

 thus causing them to have the appearance of an elongated Y, when 

 seen from this aspect. Both the pubis and ischium are of a com- 

 paratively short and slender type of structure, and the latter usually 

 has an obturator process like that of the Ornithopoda. The astra- 

 galus is usually closely applied to the tibia, and not unfrequently 

 gives off a long flattened process lying on the anterior face of the 

 latter bone, and thus resembles the condition found in young 

 Ratite Birds before the anchylosis of the two bones has taken 

 place. The metatarsals are elongated, and the feet digitigrade. In 

 the manus the number of the digits varies from four to five ; while 

 in the pes there may be either three or five. And in all cases their 

 terminal phalangeals are furnished with curved claws, which in the 

 manus are very long and prehensile, and were apparently adapted 

 for the seizure and retention of the living prey. 



It may further be observed that while the cervical vertebrae are 

 frequently shorter than the dorsals, as in the Ornithopoda, yet they 

 are sometimes longer, like those of the Sauropoda ; while the ver- 

 tebral arches in the sacrum are occasionally supported by single 

 centra, as in the latter. Finally, the femur, which may be either 

 somewhat longer or shorter than the tibia, is generally of a more 

 Crocodilian type — especially shown in its flattened head — than in 



