122 ARISTOTLE'S ANHOMCEOMERIA 



the place of bones, and containing a marrow-like liquid.* 

 This is probably a reference to the biconical masses or 

 remains of the notochord, which extends through the carti- 

 laginous centre, but exists in the long as well as the flat 

 cartilaginous fishes. 



While dealing with cartilages, it may be stated that 

 Aristotle was aware of the existence of cartilages at the ends 

 of some bones, but he did not understand the relationship 

 between them, and he erroneously speaks of the external 

 generative organs of some animals as if they were cartila- 

 ginous.! 



Aristotle did not believe that the seal had a humerus, for 

 he states that it has stunted feet,t and that it is, as it were, 

 a stunted animal, because its fore feet are just behind its 

 shoulder-blades. § The seal with which he was acquainted 

 was that now called the Monk Seal {Monachus alhiventer) . 



In P. A. iv. c. 12, 6936, Aristotle says that the inner 

 extremities of the wings of birds rest on their backs and 

 take the place of shoulder-blades, and that the breast-bone 

 is sharp-edged in all birds to facilitate their flight. It is 

 clear, therefore, that he did not recognize the presence of a 

 true shoulder-blade in birds. He knew of the existence of 

 the ostrich, but did not know anything of the form of its 

 breast-bone. 



The " ischion " of a bird, according to Aristotle, is like a 

 thigh-bone, being long and attached in some way as far as 

 the middle of the abdomen, so that, when separated, it 

 might be taken for the thigh-bone, and the "thigh-bone," 

 between it and the leg, to be some other bone.jl He con- 

 sidered the " ischion," running along and hidden to a large 

 extent within the abdomen, to be like a thigh-bone, whereas 

 it is the thigh-bone ; on the other hand, he considered the 

 leg proper to be the thigh, and the shank or tarsus to be the 

 leg. 



This explanation of his views agrees with certain im- 

 portant statements made by him. He states that, although 

 birds are bipeds, they cannot stand erect, and that they are 

 enabled to stand as they do by reason of their " ischia " 

 being long and extending forwards along the abdomen, so as 

 to bring the legs to or near the centre of the bird's body.^ 

 He also says that the " ischion " is like a thigh and of such 



* H. A. iii. c. 8. + Ihid. i. c. 10, s. 4. 



I Ihid. i. c. 1, s. 9. ^ Ihid. ii. c. 1, s. 7. 



II ibid. ii. c. 8, s. 1. •! P. A. iv. c. 12, 695rt. 



