LABYRIMTHODONTA OR LABYRINTHODOXTS. 



245 



Labyrinthodonts are found in the Carboniferous and 

 Triassic rocks, and FlQ - 285 - 



some of the species 

 are of gigantic size, 

 having in some 

 cases a skull three 

 or four feet long, 

 and a body vastly 

 more bulky, prob- 

 ably, than that of 

 an ox. Represen- 

 tatives of this or- 

 der have left their 

 foot-prints in the 

 Connecticut river 

 sand-stone, each foot-print being twenty inches long. 



Magnified Cross-section of about one quarter of 

 a tooth of a Labyrinthodont. 



PRINCIPAL TOPICS CONSIDERED IN CHAPTER II., SECTION V. 



SUB-SECTION I. 



The Batrachia considered as a Class. Origin of the name. Where they lay 



their eggs. The young. Skull. Breathing apparatus. Heart. Classifi- 

 cation. 



SUB-SECTION II. 



The Order of Anoura. Origin of the name. Form. Skin. How they 



secure food. The young. True Frogs. " Tree-toads." Toads. Eggs of 



Toads. Eggs of Frogs. 



SUB-SECTION III. 



The Order of Urodela. Origin of the name. Form and Structure. Sala- 

 manders proper. Tritons. Amphiumidaa or "Congo Snakes." Sirenidee or 



Siredons, etc. 



The Order of Apoda.- 



SUB-SECTION IV. 



-Form. Size. Where found. Eyes. Scales. 



SUB-SECTION V. 

 The Order of Labyrinthodonta. Why so named. Where found. - 



Size. 



