CONNECTING LINKS IN CLASSIFICATION. 5 



In previous volumes of this series* we have endeavoured to give 

 the reader some general notions of the form, life, and manners 

 of the branches of the animal kingdom known as Zoophytes, 

 Mollusca, Articulata, and Pisces. We now continue the superior 

 sub- kingdom (to which the fishes also belong) of the Vertebrated 

 Animals, so called from the osseous skeleton which encircles their 

 bodies, in which the vertebral column, surmounted by the cranium, 

 its appendage, forms the principal part. 



The presence of a solid frame in this series of animals admits of 

 their attaining a size which is denied to any of the others. The 

 skeleton being organized in such a manner as to give remarkable 

 vigour and precision to all their movements. 



In the vertebrated animals the nervous system is also more 

 developed. There is, consequently, a more exquisite sensibility in 

 them than in the classes whose history we have hitherto discussed. 

 They possess five senses, more or less fully developed, a heart, a 

 circulation, and their blood is red. 



We have now to deal with a class advanced above that of fishes, 

 that of Reptilia, which is divided as follows : 



AMPHIBIA (BATRACHIA, Cuv.) 



Animals having ribs or processes, or short, slight, and free ver- 

 tebrae, forming a series of separate centrums, deeply cupped at 

 both ends, one of which is converted by ossification in the mature 

 animal into a ball, which may be the front one, as in the Surinam 

 Toad, Pipa, or the hind ones in the Frogs and Toads, Rana. The 

 skin is nude, limbs digitate, gills embryonal, permanent in some, 

 in most lost in metamorphosis, to be succeeded by pulmonary 

 respiration, or both ; a heart with one ventricle and two auricles. 

 They consist of : 



I. OPHIOMORPHA. 

 Caeciliadse or Ophiosomae. , 



II. ICTHYOMORPHA. 



Proteidse or Sirens, Proteus, Newts, and Salamanders. 



* " The Ocean World," from the French of Louis Figuier. The Insect World," 

 from the French of the same author. 



