THE PRINCIPAL SPECIES OF POISONOUS SNAKES 125 
T'otal length, 1,520 millimetres ; tail 140. 
Habitat : Western North America, from British Columbia to 
South California, eastwards to Assiniboia, Dakota, Nebraska, 
Kansas, and Western and Southern Texas; Northern Mexico. 
According to Holbrook, this reptile feeds upon young rabbits, 
squirrels, rats and other small mammals. It lays its eggs in 
August, and the young are hatched at once, and are capable of 
seeking their own food. : 
In captivity as well as under natural conditions the Mottled 
Rattle-Snake is an excessively irritable species. ‘‘ The noise of 
the wind,” says Brehm, “or even the distant view of a man or 
animal, are sufficient to irritate it. It then coils itself up in a 
spiral, and places its head and tail in the centre of the disc thus 
formed, in a state of absolute immobility. After a short interval 
the creature raises its head to a height of about 8 to 12 inches 
above the ground, curves its neck in the shape of an 8, and 
elevates its tail into a vertical position and shakes it vigorously, 
whereupon the strident noise caused by the rattle is heard. So 
rapid are the movements communicated by the Crotalus to its tail 
that they can scarcely be distinguished. So long as the Crotalus 
believes itself menaced it remains in the position that we have 
just described, and continues to sound its rattle. If one withdraws 
from the irritated snake, the sound gradually lessens and ceases, 
to begin again more vigorously when the reptile is once more 
approached.” 
The bite of these snakes is exceedingly dangerous. Pigs wage 
an inveterate war against them and devour them. 
At the Pasteur Institute at Lille, I have kept several of these 
reptiles in captivity for eighteen months and longer. They 
invariably refused their food, and I always had to resort to 
artificial feeding. They are easily capable of withstanding a 
prolonged fast. 
(4) C. durissus (Common Rattle-Snake).—7 or 8 longitudinal 
