90 HALF-HOURS IN THE GREEN LANES. 



ceous, afford us illustration of true birds with reptilian 

 affinities. The former had a long tail, like a lizard, 

 feathered to the tip ; and other reptilian characters 

 the latter had bi-concave vertebrae, a reptilian 

 tail, and mandibles in which teeth were implanted. 

 The fossil reptiles, on their side, afford us species 

 having a similar leaning towards birds. The 

 Pterodactyles, or flying lizards, of the secondary rocks 

 in many respects present us with ornithic features, 

 The Campsoynathus was another bird-like reptile that 

 walked on two legs. So that it would seem as if the 

 gulf of separation between the birds and the reptiles 

 was not so wide as we have been in the habit of 

 hastily supposing. 



Our British snakes are neither numerous nor very 

 harmful. The very name is a terror to most people, 

 and as Dr. Gooke remarks, " very few possess 

 courage enough to attempt staring one out of 

 countenance." The reason of the peculiar stony 

 glare of snakes' eyes is due to their not possessing 

 eyelids. Eyelids are not required, for the simple 

 reason that the outer layer of the skin is stretched 

 like a film over the eyes. Hence their power of 

 gazing so fixedly, and without winking. When 

 snakes shed their skins, this part over the eyes is 

 shed along with the rest, and that, perhaps, is the 

 only time when a snake really winks. The com- 

 monest species with us, and in fact, in Europe, is the 

 Ringed Snake (Tropidonotus natrix). It is absent 

 from Ireland, for the geological reasons already 



