r.EPTILIA, RATRAC'HIA AND MAMMALIA. 467 



Thus we find that the lizards, the snake, the toad, the 

 newts, the mole, the common shrew, the bank vole and the 

 hare,* all present in England and in Jersey, are absent from 

 both Gnernsev and Ireland, while the frog, which must have 

 been an earlier migrant, is present in both. 



A readv inference, and perhaps a correct one, is that 

 Guernsey must have become separated from the mainland at 

 about the same period as Ireland. The exceptions are that 

 the slow-worm and the field vole, which are present in Guern- 

 sey, are absent from Ireland. It may be that these two have 

 been introduced into Guernsey with grain or other produce 

 from the opposite coast. 



It will have been noticed that I have mentioned the 

 lizards as not having reached Guernsey, when as a matter of 

 fact, one species — the green lizard — is present. This I am 

 fairly certain has been introduced from the sister island on the 

 following grounds : ScharfF states that the extension of the 

 animals named took place first from the East, then from the 

 South-east, and lastly from the South. He does not give a 

 reason for this order, but it is evident that a region slowly 

 recovering from glaciation would first become tenanted by 

 animals from the higher latitudes and that southern forms 

 would be tardy in their arrival. Now the green lizard is from 

 either the South or South-east, and must consequently have 

 been one of the last to arrive. 



We have seen that the toad found a water barrier be- 

 tween the Continental coast and Guernsey, and yet it must 

 have long preceded the lizard. The green lizard breeds 

 comparatively slowly, producing but from twelve to twenty 

 young ones in a season, and these do not wander far, so that 

 its spread must have been slow, while the toad produces many 

 hundreds, and they scatter rapidly. All who have walked the 

 country roads in districts where the toad is found, dinging May 

 or June, and especially after a heavy shower, must have been 

 struck with the myriads of little toads they come upon, ener- 

 getically hopping in all directions. So great is their number 

 that many good people believe they come down with the rain. 

 Having few enemies and food suppl}'^ being abiuidant, a high 

 percentage of these young ones reach maturity and form new 

 centres of dissemination, so the extension of the toad must 

 have been very rapid. It came, moreover, from a higher 



* A hare occurs in Ireland, but of another species, viz., Lepus tiviidus, the 

 " Arctic Hare," which did not arrive in same course of migration, but caiue from 

 Scandinavia, via. Scotland, while there was land connection there. 



The Smooth Newt is also present in Ireland, but must have been introduced, 

 for the species is one of the latest migrants.— See Scharff's "Origin of the European 

 Animals." 



