BETWEEN TYPICAL EEPTILES AND OTHER ANIMALS. 171 



the ischium more prolonged forward, tlian is the case with Cro- 

 codiles. 



In Monitor the femur is straighter than in Crocodiles ; and be- 

 hind the proximal articulation the bone is compressed, and termi- 

 nates in a strong inner trochanter, of which condition there is 

 hardly a trace in Crocodiles. The distal ends are similar ; but the 

 fibula articulates with the outer side of the distal end in 

 Lizards. 



The tibia and fibula are not unlike those bones in Croco- 

 diles, except that the Lizard fibula is somewhat compressed, so as 

 to have a ridge down each side ; and the tibia, instead of being 

 subquadrate at its distal end, is compressed from back to front, 

 and more expanded from side to side. 



The proximal row of tarsal bones is usually anchylosed to- 

 gether ; and the part corresponding to the heel of the os calcis 

 is much less developed than in a Crocodile. The distal row seems 

 to similarly consist of one or two small bones. 



Except that the phalanges of the fifth digit are suppressed, the 

 arrangement of the other bones of the hind foot is similar in the two. 

 In Lizards the proportions of the bones are different, the fourth 

 metacarpal being the longest and strongest ; the claw-phalanges 

 are similarly compressed from side to side. The bones of Lizards 

 and Chameleons are much thinner than those of Crocodiles ; and all 

 the limb-bones differ from those of Crocodiles in having epiphyses. 



The Blindworms have no special resemblance to Crocodiles. 

 Their ribs throw off a tubercle just behind the articular head 

 which looks as though it might foreshadow double-headed ribs ; 

 but the process has no attachment. Between the dorsal vertebrae 

 which bear ribs, aiid the caudal vertebrae with anchylosed chevron 

 bones, are two or three sacral vertebrae, which have the transverse 

 processes specially modified, sometimes double, as in Python, but 

 in no respect like the Crocodile's. 



§ 5. On the Bhynchocephalian Characters of Crocodiles. 



Hatteria resembles Crocodiles in having the quadrate bone 

 firmly wedged in the skull, but differs in the relations of the bone ; 

 for although a malar arch extends from the maxillary to the base 

 of the quadrate, as in Crocodiles, the quadrato-jugal bone does 

 not intervene between the quadrate and the malar. The quadrate, 

 too, is nearly vertical, and sends a long straight wing inward 

 overlapping the pterygoid in front, m uch after the manner of the 



