262 THE MICROSCOPE. 



simple opening to a complicated mouth we trace a series 

 of differentiations. The alimentary canal is at first a mass 

 of cells, then a variety of assimilative sacks or spaces, then 

 a simple canal, then a complicated canal, then a canal 

 formed of oesophagus, stomach, small intestines and large 

 intestines. With this increasing complication there is an 

 accompaniment of accessory organs, liver, parotis, pan- 

 creas, spleen, &c., secreting matters indispensable to the 

 proper preparation of the food before it can be as- 

 similated." 



Division of Animal Kingdom. The Animal Kingdom 

 is primarily divided into : 



(Hcemastomata ..... 1. Vertebrata. 

 ,, . . (2. Annulosa. 



Neurostomata . . . . { 3 Mollusca. 



4. Ccelenterata. 



5. Protozoa. 



Which are again divided into sub-kingdoms; each 

 sub-kingdom being distinguished by its peculiar typical 

 forms. Commencing from the lowest, we have, 1st. 

 Protozoa, divided into : 1. Gregarinida. 2. Rhizopoda. 



3. Infusoria. 



The next sub-kingdom, that of the Ccelenterata, is divided 

 into : 1. Hydrazoa. 2. Actinozoa. The typical form of 

 first is the Hydra: its modifications, the Sertulariadce, 

 Diphydce, Hydramedusce, &c. The typical form of second, 

 Actinozoa, is Actinia ; others, Lucernaria, Beroe, &c., its 

 modifications are exhibited in other Anthozoic polypes. 



Sub-kingdom Annulosa, presents difficulties of classifi- 

 cation, owing to the great diversity of forms included 

 among them ; but is primarily divided into three great 

 groups. 1st. Arthropoda. 2d. Annulata. 3. Annuloida. 



The first, embracing annulose animals having articulated 

 members; the second, those without articulated members, 

 but having a ventral chain of ganglia; and the third, those 

 whose nervous system is composed of cords with one or 

 more ganglia, not disposed in a ventral chain. The whole 

 are arranged in the following classes : 



I. Arthropoda: I, Crustacea; 2,Arachnida; 3,Insecta; 



4, Myriapoda. II. Annulata: I, Annelida; 2, Suctoria. 

 III. Annuloida: 1, Scolecida ; 2, GepJiyrea ; 3, JZchino- 

 dermata; 4, Rotifera. 



