ZOOLOGY. 511 



these stages are at the same time also classes ; they should, 

 for uniformity's sake, retain the latter name. 



3142. The animal kingdom accordingly divides into 

 four great districts or circles. 



CIRCLE I. Intestinal Animals, Oozoa Protozoa. 



II. Vascular Sexual animals Conchozoa. 



III. Respiratory Cutaneous,, Ancyliozoa. 



IV. Sarcose Cephalic Vertebrata. 



C. ANIMAL CLASSES. 



3143. The animal Classes may be designated as the 

 self-substantial representation of a stage in the develop- 

 ment of an anatomical system or of the inferior organ of 

 sense, and in the Sarcose animals of these systems them- 

 selves or of the cephalic senses. 



3144. There are then as many classes as there are 

 stages of development or systems. Thus the intestinal 

 system separates into pharynx or stomach, intestine and 

 absorbents. 



3145. The vascular system into veins, arteries, and 

 hearts. 



3146. The respiratory system into branchial mem- 

 brane or skin, into branchiae, and into lungs or trachea?, 

 i. e. air-tubes. Taken in a strict sense, such divisions do 

 not constitute classes, as has been already remarked. 



3147. It is only the animal systems, which do not 

 divide into several functions, but remaining upon a level 

 with each other, are simply repeated in the higher 

 organs of sense. 



First Province. Splanchnozoa, Dermatozoa. 



FIRST CIRCLE. INTESTINAL ANIMALS, OOZOA. 



3148. The intestinal animals are nothing but depressed 

 cysts. They rank therefore upon the lowest stage of 

 development, and consist of mucus or granular nervous 

 mass Protozoa, Gelatinose animals. 



3149. It is an established fact that, with animals as well 

 as plants, the first function consists in imbibition or 

 absorption, and the body must consequently be an 



