HISTOKY. 3 



stomachic dilatation. Pyloric coeca are close to the stomach, 

 variable in number ; there are even some, like the majority of 

 the cartilaginous fishes, which have none whatever. Two 

 bodies are situated along the spine, which have the function 

 of testicles, and open towards the vent, and which are much 

 enlarged in the spawning season. The scales become harfler 

 with age. Not being provided with lungs, they have no voice, 

 but several can emit grunting sounds. They sleep like other 

 animals. In the majority the females exceed the males in 

 size ; and in the Eays and Sharks the male is distinguished 

 by an appendage on each side of the vent." 



' Aristotle's information on the habits of fishes, their migra- 

 tions, mode and time of propagation, utility, is, as far as it 

 has been tested, surprisingly correct. Unfortunately, only too 

 often we lack the means of recognising the species of which 

 he gives a description. His ideas of specific distinction were 

 as vague as those of the fishermen whose nomenclature he 

 adopted ; it never occurred to him that such popular names 

 are subject to change, or may be entirely lost with time, and the 

 difficulty of deciphering his species is further increased by the 

 circumstance that popular names are often applied by him 

 to . the same fish, or that different stages of growth are 

 designated by distinct names. The number of fishes known 

 to Aristotle seems to have been about 115, all of which are 

 inhabitants of the iEgean Sea. 



That one man should have discovered so many truths, and 

 formed so sure a base for Zoology, is less surprising than the 

 fact that for about eighteen centuries a science which seemed 

 to offer particular attractions to men gifted with power of 

 observation, was no farther advanced. Yet this is the case. 

 Aristotle's disciples, as well as his successors, remained satis- 

 fied to be his copiers or commentators, and to collect fabulous 

 stories or vague notions. With very few exceptions (such 

 as Ausonius, who wrote a small poem, in which he describes 



