98 



HIGH SCHOOL ZOOLOGY. 



son in the hollows of fossil ti-ees in the coal-measures of Nova Scotia, 

 were as small as many of our Salamanders. Many resembled the Ganoids 

 as to the skin-bones of the head, but the notochord was persistent 

 throughout life as in the Dipnoi. 



Fig. 72.— Siphomips mexicanus. (After Brehm). 



24. The remaining living order, the Gymnophiona, is inter- 

 esting, because it embraces forms which, through adoption of a 

 burrowing habit, have undergone, the loss of limbs and eyes, and 

 have acquired a hardened skin provided with horny rings. 

 They are represented both in the tropics of the Old and New 

 Worlds (the most northern form is Siphonops mexicanus, Fig. 

 72.), and they appear to be most nearly allied to Amphiuma, 

 which they resemble in depositing necklace-like strings of eggs. 



