Book Notices. ' 503- 



"There is one point to be mentioned in connection with the adapta- 

 tion of the giraffe to its surroundings, before passing on, and this 

 relates to its coloration. When seen within the enclosures of a mena- 

 gerie — where, by the way, its pallid hue gives but a faint idea of the 

 deep chestnut tinge of the dark blotches on the coat of the wild male — 

 the dappled hide of a giraffe appears conspicuous iu the extreme. We 

 are told, however, that among the tall kameel-dhorn trees, or giraffe - 

 mimosas, on which they almost exclusively feed, giraffes are the most 

 inconspicuous of all animals ; their mottled coats harmonizing so exactly 

 with the weather-beaten stems and with the splashes of light and- 

 shade thrown on the ground by the sun shining through the leaves, 

 that at a comparatively short distance even the Bushman or Kaffr is 

 frequently at a total loss to distinguish trees from giraffes or giraffes 

 from trees." 



Previous to the discovery by Cuvier, in 1818, that the minute jaws 

 found in the Stonesfield slate of the lower Jurassic were those of a 

 mammal, mammals were supposed to have been unknown before the 

 Tertiary period. It has been concluded that these jaws are those of a 

 marsupial— the lowest of all living mammals. Some of the Jurassic 

 mammals of Dorsetshire and North America may be more nearly allied 

 to insectivores. There seems to be a likelihood that some of the- 

 Jurassic mammals were actually the link connecting marsupials with 

 insectivores. 



The distinction between crocodiles and alligators is not a well known* 

 one. In the lower jaw of crocodiles there are invariably fifteen teeth ; 

 the teeth of the two jaws interlock when the mouth is closed ; when 

 the jaws are in opposition, the first tooth on each side of the lower jaw 

 is received into a pit in the palate of the skull, while the fourth lower 

 tooth bites into a notch in the side of the skull, and is distinctly visible 

 externally in the living animal. The alligator, on the other hand, has 

 never less than seventeen lower teeth ; the upper teeth bite on the 

 outside of the lower without interlocking. The first and fourth lower- 

 teeth are received into pits in the skull,, and are invisible when the 

 mouth is closed. Modern crocodiles show advance in organization over 

 those of the Jurassic period, in the backward placing of the internal, 

 nostrils, and in the ball-and-socket vertebrae. Change in mode of life 

 has wrought a transference of body armour from the under surface to- 

 the back of the creature. 



The fins and tails of fishes are of two types — the fringe-like and the 

 fan-like. The former is the older type, and has gradually become 

 modified into the latter as best adapted for speed in locomotion. A 

 representative of the fringe-like type is the Australian lung-fish, allied 

 to Ceratodus, the name applied to certain teeth found in the Trias of 

 Europe. The lung-fish is the oldest type of vertebrate now living. 



The term " living fossil" is applied to types which, though more or- 



