130 ARISTOTLE'S ANHOMCEOMERIA 



darker.* Aristotle says that all the teeth of the seal are 

 sharp and interlocking, because it is very closely allied to 

 fishes. t This is true, but the reason given sounds strange; 

 the seal being now classed M^ith the otter and other carni- 

 vora. He gives a fair general description of the gastric 

 mill in lobsters and crabs. He says that it is in the part 

 of the stomach which is near the mouth, and that there are 

 three teeth, two lateral ones and one below, t 



The gastric mill is in the hinder part of the large or 

 cardiac portion of the stomach, into which the short, nearly 

 vertical gullet enters. Numerous parts make up the gastric 

 mill, but three are very conspicuous, two lateral and ap- 

 proximately horizontal teeth and a median dorsal one 

 between the posterior ends of the lateral ones. 



In H. A. iv. c. 4, s. 7, Aristotle says that KochUas, 

 probably Helix, has small, sharp, and delicate teeth. This 

 seems like a reference to the lingual teeth, and, if so, the 

 statement shows that he closely examined the structure of 

 the mouth of this animal. He also says that the Kochloi, 

 by which some gastropods are meant, have two teeth in 

 addition to a tongue. § These two teeth may be merely the 

 horny jaws of the gastropods. 



Aristotle says that the sea-urchin has five inwardly 

 curved teeth. i| These teeth w^th their pyramidal sockets 

 and the numerous pieces of framework supporting the 

 whole are called "Aristotle's lantern," and form a compara- 

 tively large structure projecting within the shell of the sea- 

 urchin. Aristotle was the first to direct attention to it, but 

 it was the shell of the sea-urchin divested of its skin which 

 he compared to a lantern. 



Aristotle makes the following interesting statements 

 about the shedding of teeth : — " Man and some other 

 animals, e.g., the horse, mule, and ass, shed their teeth. 

 Man sheds his front teeth and no animal sheds its 'molars,' 

 while pigs do not shed any at all. Whether or no dogs 

 shed their teeth is a disputed point ; some believe that they 

 do not, others that they shed their canine teeth only, but it 

 has been observed that dogs shed their teeth, like Man, only 

 the shedding escapes notice because the teeth are not shed 

 until new ones, similar to them, have been developed under- 



* H. A. ii. c. 3, s. 12. f H. A. ii. c. 3, s. 9 ; P. A. iv. c. 13, 6976. 



I H. A. iv. c. 2, s. 11 ; P. A. iv. c. 5, 679ff. § P. A. iv. c. 5, 6786. 



II H. A. iv. c. 5, s. 5 ; P. A. iv. c. 5, 680rt. 



