l86 FAUNA OF SHROPSHIRE. 



CHAPTER VI. 

 REPTILES. 



WHAT is a Reptile ? The word means literally any- 

 thing that creeps, but in scientific phrase is restricted 

 in its application to the creatures known as Snakes, Lizards, 

 and Tortoises. It is also sometimes applied to Frogs, Toads, 

 and Newts, but, as will be shown later on, those animals 

 differ widely from the true Reptiles in many respects. With- 

 out going into anatomical details, it will be sufficient to state 

 a few of the most marked peculiarities of the Reptiles. As 

 distinguished from Mammals and Birds we notice first that 

 they feel cold to the touch, and the blood is cold ; this 

 may be due, in some degree, to the circulation being 

 imperfect, the heart having only three instead of four 

 chambers. All Reptiles breath by lungs, and at no period of 

 their lives are provided with gills. The young undergo no 

 metamorphosis, and are produced from eggs ; these are not 

 hard-shelled, however, but are enclosed in a leathery envelope. 

 Sometimes this envelope ruptures and liberates the young 

 before the egg is extruded from the body, and the animal 

 is then said to be ovo-viviparous. The Viper, the Blind 

 Worm and the Common Lizard are British examples of 

 this phenomenon, and it is possible that our cold climate 

 has induced this state of things, as it would be advan- 

 tageous to the species for the young to be born alive, 

 rather than run the risk of perishing if exposed to the 

 elements. In this way we can account for the fact that three 

 out of the six reptiles found in Britain are ovo-viviparous 



