80 HALF-HOURS IN THE GREEN LANES. 



dition, in endeavouring to explain such a notable face, 

 has done so by making Saint Patrick banish them 

 from the Green Isle ! But England, in a similiar 

 manner, has not so many indigenous species of 

 reptiles as the adjacent continent. Professor Forbes 

 showed that the cause of this paucity of species in a 

 westerly direction is due to the physical disturb- 

 ance which separated England from the continent, 

 and Ireland from England, before their thorough 

 distribution had been carried on to the latter country. 

 It is certain that the formation of the German Ocean 

 and the Irish Sea are among the most recent of 

 important geological phenomena, and it is equally 

 certain that the present distribution of animals and 

 plants can only be accounted for by reference to 

 phenomena of this kind. 



Professor Quatrefages has shown that the young 

 Frog, after it has left the egg, and before it has 

 become a larva, is still in a semi-embryonic condition. 

 At this period, the digestive tube and its appen- 

 dages are very rudimentary. The greater portion 

 of the body is filled by a large mass of yolk, enclosed 

 by the skin, and the development of the larval frog 

 proceeds by the absorption of this alimentary matter. 

 The young tadpole of the frog at first exhibits no 

 trace whatever of limbs. It swims about like a fish 

 by the action of its tail, which is a most important 

 and extensive organ, longer and wider than the 

 body, supported by a prolongation of the vertebral 

 column, and moved by powerful muscles. Shortly 



