ICHTHYOPSIDA (FISH-LIKE FORMS). 



Under this name are grouped fishes and batrachians, 

 since they are alike in certain important respects. Thus 

 they have, either as larvae or adults, functional gills, they 

 have lateral-line organs, they have median fins, and the 

 blood is cold. Besides these there are several other points 

 of union, notably in the development, especially promi- 

 nent being the absence of two embryonic structures, the 

 amnion and allantois, which occur in higher forms. The 

 Ichthyopsida is divided into two classes: 



CLASS I. PISCES (FISHES) (p. 33). 

 CLASS II. BATEACHIA, OR AMPHIBIA (p. 49). 



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