22); THE VIVARIUM. 
best to get out of the way of those who disturb them ; still there 
is the danger of their being trodden upon and immediately resent- 
ing the accident. They are more numerous, as I have said, in 
this country than the Grass Snake, the chief reason for this 
being, I think, that while the latter deposits from fifteen to 
thirty eggs, rarely more, in some manure or leaf-heap, or similar 
situation, which are always running the risk of never being 
hatched, either through an insufficiency of heat or through the 
destruction by some enemy, the Viper produces, at one time, from 
thirty to fifty little Viperlings all ready and able to fight their 
way in the world. Besides this, the Adder, though it will not 
often live or feed in confinement, is the hardier of the two 
Reptiles. 
Size, of course, is not a safe guide in distinguishing the Viper 
from the Common Snake, though the latter is far larger, when 
full-grown, than the former in a similar condition. There is in 
England a third Snake, which in size and colouring resembles 
the Adder far more closely than does 7. natrizv. Unfortunately, 
this beautiful, harmless, and interesting little creature, which 
will be described in another place, is not only rare here, but is 
confined to certain counties and districts. 
Anyone who has once carefully compared, while seeing them 
together, the Viper and the Common Snake, will for the future 
have no difficulty in distinguishing the one from the other. The 
Common Snake (7. natriv) has nearly always a bright yellow 
collar, bordered behind by a second collar, which is never absent, 
of a deep black colour. The ground-colour of this Reptile’s body 
is grey, olive, or brown, marked with rows of alternate black 
spots. The labial shields are bright yellow, and are divided, 
seemingly, from each other by black lines ; the under-parts of the 
animal are generally of a dull bluish or lead colour, marbled with 
black, or the markings are yellowish-white and black, the former 
colour being most plentiful near the head and gradually decreasing 
in quantity towards the tail, where black predominates. In ac- 
cordance with this Snake’s generic name, most of its scales are 
strongly keeled. They are placed in nineteen rows. ‘The 
ventral scales number from 160-190, and the sub-caudals are in 
from fifty to eighty-eight pairs. There is one pree-ocular shield 
