Notes, iv, 13 — 14. 253 



41. As to continuity of brain and spinal cord, and its supposed purpose, of. ii. 7, 1 1. 



42. Heat is the instrument of the soul in motion, as in all operations (i. I, Note 13). 

 Cetacea therefore that move actively must have much heat ; and this again necessitates 

 a perfect organ to regulate heat, and such is the lung. 



43. Cf ii. 12, Note 4. 



44. Cf. iii. I. Note "] ; H. A. ii. I, 52. In the seals, says Owen {Odontog. i. 506), 

 "the coadaptation of the crowns of the upper and lower teeth is more completely 

 alternate than in any of the terrestrial Carnivora, the lower teeth always passing into the 

 interspace anterior to its fellow in the upper jaw." 



45. A. means that the anterior limbs of bats though they are wings yet have claws, 

 and so resemble feet and are unlike the wings of a bird ; but at the same time they 

 do not so closely resemble the fore-limbs of a quadruped as to make the bat strictly 

 quadrupedous. A. knew that bats are viviparous and suckle their young ; for he speaks 

 of these animals as having cotyledons in their uterus {H. A. iii. i, 31), and groups 

 them with the hare and the rat among viviparous animals with teeth in both jaws. 



(Ch. 14.) 1. In the ostrich and other Ratitse the barbs of the feathers are dis- 

 connected, so that they come to resemble long hairs, and, owing to their want of firmness, 

 are useless for flight. 



2. Cf. ii. 14, Note i. 



3. The head and neck are naked, or covered with only a short downy plumage. 

 Cf. ii. 9, Note 9. 



4. The foot of the ostrich has two stout toes, connected at the base by a strong 

 membrane. Of these toes the internal is much the larger, and is furnished with a 

 thick hoof-like claw, but the external and smaller toe is clawless. Aristotle had 

 probably never himself seen an ostrich ; for, had he done so, he would scarcely have 

 spoken of its foot as having two hoofs. That the ostrich is a kind of link, uniting birds 

 with mammals, is not a fancy confined to Aristotle. The vulgar opinion in Arabia still 

 makes it the product of a camel and a bird, as in the days when it got the name, 

 already used for it by Pliny, of Struthio-camelus. The height of the bird, its long neck, 

 its bifid foot, its frequentation of the desert, its patient endurance of thirst, and 

 possibly the comparative complexity of its digestive organs, were doubtless the grounds 

 of this strange notion. 



