GRAND DIVISIONS. 9 



Linneus left them, or nearly so. Insecta is di- 

 vided into three classes, to which is prefixed a 

 class taken from Vermes. They are Annelida, 

 Crustacea, Jlrachnida, and Insecta. The re- 

 mainder of the class Vermes is divided into Mol- 

 lusca, Echinoderma, Intestina, Jlcalepha, Polypi 

 and Infusoria. The subdivisions are adopted in 

 this text-book. 



GRAND DIVISIONS. 



THE SUBJECTS OF ZOOLOGY ARE DISTRIBUTED 

 INTO FOUR GRAND DIVISIONS J BECAUSE ANIMALS 

 APPEAR TO HAVE BEEN ORGANIZED UPON FOUR 



GENERAL PLANS. 



I. RADIATED ANIMALS or ZOOPHYTES, 



In this division the sentient principle is lodged 

 in, or, in some unknown manner, attached to, a 

 medullary globule, spheroid or ring, with radiat* 

 ing branches. 



Animals of this class are but little more com- 

 plicated in their structure than plants. No dis- 

 tinct system of nerves nor any organs of sense, 

 have been discovered. Feint vestiges of circula- 

 tion are with difficulty perceived. Their respi- 

 ratory organs are mostly on the surface of the 

 body. Some receive their food through a mouth^ 

 others through pores. 



Some animals of this division may be cut across^ 

 and both parts will live. This is explained by 

 supposing the animal to consist of a column or 

 pile of distinct animals, and that the transverse cut- 

 ting produces a mere separation of a column of 

 individuals into several shorter columns. 



