43-2 



BATRACHIA. 



THIS Class is intermediate between the Reptiles and the Pishes. 

 From the latter, Batrachians are distinguished by the structure of 

 the limbs, which, as in higher Vertebrates, consist of a proximal ele- 

 ment (humerus, femur), two propodials (radius and ulna, tibia and 

 fibula), acarpus or tarsus, metacarpalsormetatarsals, and phalanges ; 

 from the former, they are distinguished, as far as existing forms are 

 concerned, by the absence of a basioccipital ossification, the articula- 

 tion of the skull with the vertebral column being by means of two 

 condyles furnished by the exoccipitals, by the absence of amnion or 

 allantois in the embryo, and, with a few exceptions, by the passage 

 through a larval, branchiferous stage after leaving the egg, or by 

 undergoing what are called " metamorphoses." The body is naked, 

 or, if scales are present, these are imbedded in the skin. However, 

 the extinct Labyrinthodons or Stegocephala agree with the Rep- 

 tiles in the possession of an ossified basioccipital, and a nearly 

 complete passage appears to be effected from the Batrachians to 

 the Reptiles through that group and the Rhynchocephalia. Leaving 

 aside the Stegocephala, Batrachians may be divided into three 

 Orders, viz. : 



I. ECAUDATA, Frogs and Toads. 

 II. CAUDATA, Newts and Salamanders. 

 III. APODA, Caocilians. 

 All three of which are represented in the Oriental Region. 



Order I. ECAUDATA. 



Four limbs and no tail. Radius and ulna and tibia and fibula 

 confluent ; metatarsus (astragalus and calcaneum) elongate, forming 

 an additional segment in the hind limb. Frontal bones confluent 

 with parietals. 



