182 THE MICROSCOPIST. 



CLASS III. MYRIAPODA. Ex., Centipedes. 



CLASS IV. INSECTA.- Ex., Anoplura (lice). Mallophaga 

 (bird lice). Thysanura (spring-tails). Hemiptera. Or- 

 thoptera. Neuroptera. Diptera. Lepidoptera. Hyme- 

 noptera. Coleoptera. 



SUB-KINGDOM V. MOLLUSCA. 



DIVISION A. MOLLUSCOIDA. A single ganglion, or pair 

 of ganglia ; heart imperfect, or none. 



CLASS I. POLYZOA. Ex., Sea-mats (Flustra). 



CLASS II. TUNICATA. Ex., Ascidia (Sea-squirts). 



CLASS III. BRACHIOPODA. Ex., Terebratula. 



DIVISION B. MOLLUSCA PROPER. Three pairs of gan- 

 glia ; heart of at least two chambers. 



CLASS I. LAMELLIBRANCHIATA. Ex., Oyster. Mussel. 



CLASS II. GASTEROPODA. Ex., Buccinium. Helix. 

 Doris. 



CLASS III. PTEROPODA. Ex., Cleodora. 



CLASS IY. CEPHALOPODA. 



Order 1. Dibranchiata. Ex., Poulp. Paper Nautilus. 



Order 2. Tetrabranchiata. Ex., Pearly Nautilus. 



CHAPTER XII. 



THE MICROSCOPE IN ANIMAL HISTOLOGY. 



IN Chapter IX we described the elementary living 

 substance, or bioplasm, from which all organized struc- 

 tures proceed, with an outline of its morphology, chemis- 

 try, and physiology. In Chapter X we treated of Vege- 

 table Histology, or the elementary tissues and organs 

 which pertain to vegetable life. We now consider the 



