160 MR. H. G. SEBLEY ON OSSEOUS RESEMBLANCES 



found in the marsupial Phascolarctos, where the form of the arti- 

 culations, especially the distal articulation, and the form and 

 position of the muscular attachments offer a close parallel to the 

 Crocodile ; but the epiphyses and side-to-side compression of the 

 bone serve to distinguish it. The fibula of the Crocodile is also 

 nearly paralleled by Phascolarctos, which has the Crocodilian 

 form of distal end, and comes much nearer to the Crocodile in 

 form than does the fibula of the Porcupine. 



The tarsus of the Crocodile approximates closely to the mam- 

 mal type. The os calcis is quite like that of a mammal, only 

 shorter and stronger ; the astragalus is comparable with that of 

 some of the Marsupials, though it does not make a close resem- 

 blance to any genus in form. The distal row of the tarsus is 

 formed by two bones, a cuboid and a smaller naviculare ; this 

 portion of the Crocodile's tarsus is, perhaps, best compared with 

 that of a Kangaroo, in which, however, the three cuneiforms, 

 which in some shape characterize the tarsus of mammals, are 

 small and developed between the thread-like metatarsals and the 

 astragalus : these cuneiform bones are wanting in the Crocodile. 

 Some mammals, like Ox and Deer, have but one cuneiform bone; 

 and then the naviculare and cuboid are united. 



The metatarsal bones have a general resemblance to those in 

 clawed mammals. A.s in man, the inner (great) toe is the stoutest. 

 The metatarsal of the fifth digit is only represented in the Cro- 

 codile by a claw-shaped stump. The claw-phalanges are more 

 like those of marsupials than placental mammals ; but the marsu- 

 pials do not appear to have the lateral furrows which mark the 

 bones in the Crocodile. 



Crocodile bones frequently have at their terminal margins a 

 striated or wrinkled aspect, which is not seen in mammals. 



§ 2. The Avian Characters of Crocodiles. 



The Alligator, in its divided nostril, comes nearer to birds than 

 do Crocodiles ; and struthious birds, like the Apteryoc, in the 

 forward extension of the nares approximate nearer to the Croco- 

 dile type than do other birds. The palatal osseous perforation 

 under the nares of Crocodiles is present in birds, but is often 

 elongated, and extends far backward. The posterior nares in 

 many birds are anterior to the pterygoid-malar fossae, and mar- 

 gined by the vomer, malar, and palatine bones. In these features, 



