82 REPTILES 



changes due to age have been observed in pit-vipers. These 

 snakes are born with the tip of the tail, for the length of 

 about an inch, of a brilliant sulphur-yellow. When food is in- 

 troduced into the cage these young vipers communicate a 

 writhing, twisting motion to their tails, causing the latter to 

 resemble small worms, or maggots. Possibly nature has 

 provided them with this dash of brilliant colour to attract 

 small birds, lizards, or frogs within reach, as they lie coiled and 

 difficult to discern from the surrounding vegetation. This 

 feature has been observed in the copperhead snake (Ancistro- 

 don contortrix), the water-moccasin (A, piscivorus), and the 

 fer-de-lance (Lachesis lanceolaia). After the first year, the 

 yellow of the tail becomes very indistinct, and during the 

 second year it disappears altogether. 



With some of the pit-vipers, the colours of the young are 

 very brilliant, although they exhibit much the same pattern as 

 the adult. Young moccasins show brilliant shades of red and 

 yellow at birth. The adults display a dull pattern of varying 

 shades of sombre olive ; while old specimens exhibit no 

 pattern at all, the body being dull green. 



Quite different from the pit-vipers are the young of some of 

 the colubrine snakes. The young of the black snake {Bascanium 

 constrictor) are pale grey, with blotches of brown or red along 

 the back, and resemble the milk-snake (Ophibolus doliatus tri- 

 angulus). During their second year they become darker, and 

 the pattern appears diffused. The third year shows hardly a 

 trace of the spots as the black of the adult appears, although 

 the sides indicate the marking of the young. 



The chicken-snake (Coluber quadrivittatus) is remarkable, 

 as are most species of Coluber, in showing when young an en- 

 tirely different pattern from the adult, both forms being strongly 

 coloured. At the time of hatching the young chicken-snake is 

 greyish, decorated with a regular series of oblong blackish 

 saddles. As the reptile approaches maturity, the body-colours 

 change to yellow, a dark stripe appears on each side of the 

 saddle-like markings, and another on the side of the body. 

 These stripes become very distinct before the saddles begin to 

 fade. The latter change takes place usually during the third 

 or fourth year, the mature form being uniform yellow or brown, 

 traversed by four longitudinal stripes. 



