64 



GEOLOGY. 



animals are distinguished from true reptiles by the fact that the young 

 undergo certain metamorphoses after leaving the egg. In this stage 

 of their existence they breathe by external gills ; these gills 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. There are never more than two 

 vertebras coalesced to form the sacrum. The centrum of the backbone 

 is sometimes found to be unossified, forming a mere ring of bone, the 



Fig. 31.— The great Fossil Salamander from (Ening-en (Cryptobranchus homo-diluvii-testis), 



Scheuchzer, sp. 



interior being gelatinous. This form of backbone is called " Noto- 

 chordal," and is characteristic of the oldest reptilia belonging to 

 this group met with fossil in the Coal Measures, such as the 

 Anthracosaurus, Archcegosaurus, and the Triassic Labyrinthodon. 



The Salamanders are represented by the great fossil form from the 

 Miocene of CEningen {see Table-case 21), which, when first discovered, 

 in 1726, was described by Scheuchzer as "homo-diluvii-testis" the 

 man who witnessed the Deluge ! 



The tail-less Batrachia, or frogs and toads (Table-case 21), have 

 been found fossil in the same freshwater deposit, and also in the 

 Brown Coal of Bonn-on-the-Rhine. 



GALLERIES RUNNING NORTH FROM THE REPTILIAN 



GALLERY. 



There are seven Galleries running at right angles to the Reptilian 

 Gallery, about 140 feet in length; three of which are forty feet in 

 breadth, and four are of half that width. No. 1 is occupied by the 

 Library. 



CLASS 5. — PISCES (Fishes). 



The first wide Gallery (A) is devoted to the exhibition of the Fossil 

 Fishes, and contains thirty-two Table-cases, and about 260 feet linear 

 of Wall-cases. 



Here are exhibited the finest collection of Fossil Fishes ever 

 brought together in any museum. This class was always well repre- 



