310 



A COURSE ON ZOOLOGY. 



attains a length of three feet. Like the lizards, the uro- 

 dela have the singular property of replacing lost parts. 



FIG. 265. 



LARVAE OF TRITON CRISTATUS. A, condition before leaving the egg ; B, tad- 

 pole shortly after it is hatched ; C, at about the twenty -second day ; D, at 

 about the forty-second day. 



CHAPTER XXXII. 

 Pishes. 



THE general characters of fish as a class have been 

 studied in Chapter XT., the example being the carp. 



The classification of fish is based first on the nature of 

 the skeleton ; those having an osseous skeleton are called 

 teleostei, and are by far the more numerous ; those in 

 which the skeleton is cartilaginous constitute the sub- 

 class chondropterygii. The first subclass is divided into 

 orders according to the condition of the premaxillary 



