On the Classification of Fishes. 275 



Kew organs and instruments, and a new form in each. Think (to 

 'iise an ilkistration of Bonnet) but of the cocoon of the silk-worm ! 

 ilow many hands, how many machines does not this little ball 

 put in motion ! Of what riches should we not have been deprived, 

 if the moth of the silk-worm had been born a moth, without hav- 

 ing been previously a caterpillar ! The domestic economy of a 

 large portion of mankind would have been formed on a^plan 

 altogether different from that which now prevails. 



I am, &c. 



ARTICLE XLlll—On the Classijication of Fishes. With par- 

 ticular reference to the Fishes of Canada. — -By Frank Forelle. 



Fishes belong to the first department of the animal kingdom, the 

 Vertebrata, having an internal skeleton, with a back-bone for its 

 axis, yet occupying the lowest position in that department, as wiE 

 be seen by referring to the first number of this Magazine. They 

 have red blood, not warm like that of the animals comprised in 

 the first and second classes of this department, the mammals and 

 birds, but cold like that of the reptiles. They are destitute of 

 lungs, and on this account they cannot live in the air, for their 

 blood is oxygenized through the medium of water passing between 

 their branchiaj or gills. These are for the most part com- 

 posed of thin plates or laminae, fixed on arches, called the branchial 

 arches, and are covered with countless minute blood vessels, which 

 are so arranged as to present a large surface to the Avater, which 

 r^ most fishes is taken in at the mouth and expelled at the aper- 

 ture under the gill covers, so as to keep a constant current passing 

 through the gills to renew the supply of oxygen. 



Their heart is unilocular, that is, it is not divided into two 

 auricles and two ventricles, as in mammals and birds, nor yet into 

 two auricles and one ventricle as in reptiles, but has only one 

 auricle and one ventricle. The blood in its circulation passes from 

 the auricle into the ventricle and from thonce into the gills, where 

 it is brought into close proximity to the air diffused through the 

 water, and having been thus aerated is distributed by arteries 

 through the system, and returned by the veins to the auricle. 



Fishes are variously covered : some have imbricate scales, as the 

 Perch ; some have bony shields or plates, as the Sturgeon ; some 

 are covered with a rough shagreen like skin, as the Shark ; and 



