116 LIMBS OF THE CROCODILE. 



were a result of, and necessarily inclnded in, the wider 

 law of general homology. According to tlie latter law, 

 we discern in 60 and 51 a compound " pleurapophysis," 

 in 52 a " h^mapophysis," and in hs^ the "haemal spine," 

 completing the haemal arch. 



The scapulo-coracoid arch, both elements, 51, 52, of 

 which retain the form of strong and thick vertebral and 

 sternal ribs in the crocodile, is applied in the skeleton of 

 that animal over the anterior thoracic haemal arches. 

 Viewed as a more robust h^mal arch, it is obviously out 

 of place in reference to the rest of its vertebral segment. 

 If we seek to determine that segment by the mode in 

 which Ave restore to their centrums the less displaced 

 neural arches of the antecedent vertebrae of the cranium 

 or in the sacrum of the bird,^ we proceed to examine the 

 vertebra? before and behind the displaced arch, with the 

 view to discover the one which needs it, in order to be 

 made typically complete. Finding no centrum and neu- 

 ral arch without its pleurapophyses from the scapula to 

 the pelvis, we give up our search in that direction ; and 

 in the opposite direction we find no vertebra without its 

 ribs, until we reach the occiput ; there we have centrum 

 and neural arch, with coalesced parapophyses, but with- 

 out the haemal arch, which arch can only be supplied by 

 a restoration of the bones 50-52 to the place which they 

 naturally occupy in the skeleton of the fish. And since 

 anatomists are generally agreed to regard the bones 

 50-52 in the crocodile (Fig. 18) as specially homologous 

 with those so numbered in the fish (Fig. 9), we must con- 

 clude that they are likewise homologous in a higher 



' See "On the Archetype and Homologies of the Vertebrate Skeleton," 

 pp. 117 and 159. 



