DISTINCTIVE CHARACTERS OF ANIMALS. 



195 



liabitation. The soil that supports us, and gives us our daily bread, is nothing 

 but a mixture of animal and vegetable materials ; other substances indeed 

 enter into it, but the great, the important, the af-tive, and leavening con- 

 stituent is of an organized origin. These materials, then, are perpetually 

 forming, and acculViulating, and rising into an unbounded and inexhaustible 

 store-house of subsequent riches and plenty by the alternate generation 

 and decomposition of the different kinds and orders of plants and animals 

 which thus fill up, and, as we are apt to believe, encumber the rf'gions we 

 are contemplating ; regions which, though in our own day unexplored or 

 abandoned both by savage and civilized man, may, in that revolution of 

 countries. and of governments which is perpetually passintr before our eyes, 

 become, in some future period, the seat of universal dominion, the empo- 

 rium of taste and elegance, of virtue and the sciences. So the fairest 

 fields of Rome were formed out of the putrid Pontine marshes, and England 

 has become what she is, from being a land of bogs and of bhghts, of 

 wolves, wild-boars, and gloomy forests. 



LECTURE II. 



ON ZOOLOGICAL SYSTEMS, AND THE DISTINCTIVE CHAEACTEES Oli' 



ANIMALS. 



(The subject continued. ) 



In our last lecture we took a momentary glance at the history of zoology 

 as a science, noticed the primary features of the best methodical arrange- 

 ments to which it has given rise, and made some progress towards a brief 

 delineation of that of Linneus, which still takes the lead amidst the writers 

 of the present day, and is hence chiefly entitled to attention in a course of 

 popular study, generally collating it, however, with that of M. Cuvier, as 

 we proceeded. 



We observed that the Linnean system comprehends all animals of every 

 description whatever, under the six classes of mammals, birds, amphibials, 

 fishes, insects, and worms. We pursued this arrangement in an ascending 

 scale, as most consistent with the plan adopted at the opening of the pre- 

 sent course of instruction ; and commencing with the class of worms, 

 finished with that of insects. It remains for us to prosecute the same 

 rapid outline of inquiry through the four unexamined classes of fishes, 

 amphibials, birds, and mammals. 



Fishes are classically characterized in the Linnean system as being 

 always inhabitants of the water ; swift in their motion and voracious in 

 their appetite ; breathing by means of gills, which are generally united 

 by a bony arch ; swimming by means of radiate fins, and for the most 

 part covered over with cartilaginous scales. 



The class is divided into six orders ; the ordinal characters being taken 

 from the position of the ventral or belly fins, or from the substance of the 

 gills. The orders are, apodal, fishes containing no ventral or belly fins ; 

 jugular, having the ventral fins before the pectoral ; thoracic, having the 

 ventral fins under the pectoral ; abdominal, having the ventral fins behind 

 the pectoral. In all these four, the rays or divisions of the gills are bony* 

 In the fifth order, which is called branchiostegous, the gills are destitute 

 of bony rays ; and in the sixth, or chondropterygious order, the gills are 

 <iartilaginous ; al! which will be easiest explained by a few familim' ^ani- 



