64 



Amphibia — Ecaudata. 



Amphibia. 

 Gallery, 

 No. 4. 

 Table-cases, 

 Nos. 22 and 

 23. 



West Cor- 

 ridor, 

 No. 5. 

 Wall-case, 

 No. 11. 



Class 4.— AMPHIBIA. 



In Wall-case No. 11, and in Table-cases Nos. 22 and 23, are 

 placed the fossil Ami'HIMIA or Batrachia (Frogs, Toads, Newts, 

 and Salamanders). These animals are disting-uished from true 

 reptiles by the fact that the young undergo certain metamor- 

 phoses after leaving- the egg- In this stage of their exist- 

 ence they breathe by external gills, whicli are occasionally 

 retained along with internal lungs in the adult animal. The 

 limbs are sometimes all absent, or one pair may be wanting. 

 When present, they have the same bones as in the higher 

 animals ; they are never converted into fins. The skull has two 

 occipital condyles and often a persistently cartilaginous basi- and 

 supi'a-occipital. The suspensorial apparatus of the mandible 

 is continuous with the skull. Teeth are commonly present on 

 the premaxilla, maxilla, vomer, and the dentary bone of the 

 mandible. They are usually anchylosed to the bone and are 

 simple in structure ; but in the Labyrinthodonts they are more 

 complex. There are never more than two vertebra? coalesced to 

 foi'm the sacrum. The tail is usually comparatively short. The 

 centra of the backbone are sometimes found to be unossified, 

 foi-ming- a mere ring of bone, the interior being gelatinous. 

 This form of backbone is called " Notochordal," and is cha- 

 racteristic of the oldest forms belonging to this group met 

 with fossil in the Coal Measures, such as the Atdhracosaurusy 

 Archegosaurus, and the Triassic Labyrinthodonts. 



Table-case, 

 No. 23. 



Batrachia ; 



Frogs, 



Toads. 



Order I.— ECAUDATA. (Tailless Batrachia, Frogs and 



Toads.) 



The body of the adult is short, destitute of a tail, and furnished 

 with four limbs, of Avhich the pelvic pair are the larger and 

 adapted for leaping. There are no gills in the adult. Skull 

 short and wide, with the parietals confluent with the frontals, 

 and the orbits usually undefined ; pr£esacral vertebrae few in 

 number, and generally proccslous ; there is only one sacral 

 vertebra, and the vertebral column terminates iu a long urostyle ; 

 dorsal ribs are usually absent. Ilia prolonged backwards, so as 

 to throw the acetabulum far behind the sacrum ; radius and ulna, 

 and tibia and fibula respectively fused together, calcaneum and 

 astragalus elongated. Four digits in the hand and five in the 

 foot ; an additional ossicle in the pes may represent the prehallux. 



The tailless Batrachia (frogs and toads) do not date back 

 further in time than the Upper Eocene. 



A foi'ui allied to the European genus Bohihinator occurs in the 

 Upper Miocene of Switzerland and the Middle Miocene of 

 Sansan, France. Another genus Bnfaviis, occurs in the Middle 

 Tertiary of Italy. Pelohates is found in the Miocene of Sansan, 



