VENOMOUS SERPENTS. 
191 
4. Crotalus mutus. — Remarkable by its tail armed at 
the tip, in place of the rattle^ with a hard and sharp point. 
Head covered with scales ; back carinated ; scales sur- 
mounted with a keel in the form of a tubercle. Arrives 
to the length of 10 feet ; it is the largest of all venomous 
serpents. It forms the passage to the Trigonocephalus ; 
but its physiognomy is wholly that of a Crotalus. S. 227 
+ 49. From South America. 
VIPERA. 
The third genus comprehends all the True Venomous 
Snakes that want the nasal fosse. They usually have the 
head and body covered with lanceolate, carinated scales. 
Their forms are often very heavy, and their tints of a grey 
or tawny brown. They inhabit deserts, or uncultivated 
places in the ancient world. 
1. ViPERA Arietans. — Of a strong make, and a heavy 
and hideous form ; head large, very flat, and with a muzzle 
very broad and obtuse ; nostrils vertical, extremely spa- 
cious ; head and body covered with lanceolate scales raised 
into a strong carina. S. 134 + 27. Above yellowish, 
with three rows of spots, often oscillated, 2 pairs of which 
are on the occiput. From the Cape, and the Gold Coast. 
A local variety, with brighter tints, inhabits Kordofan. 
2. ViPERA Apropos. — From the Cape. Size less, and 
form less powerful than the V. arietans ; head smaller ; 
nostrils less wide, and more lateral ; of a very dark brown, 
relieved on the upper parts by 4 rows of ocellated spots. 
S. 138 + 23. 
3. ViPERA CORNUTA. — Size small ; form extremely 
short ; eye protected above by a range of scales prolonged 
into a point ; nostrils lateral. Grey-brown, varied with 
dark-coloured spots, a central row of which runs down the 
back. PI. 124 + 22. From the Cape; very rare. 
4. ViPERA Echis. — Eye surrounded with a row of small 
scales ; nostrils narrow, near the tip of the snout, which 
is furnished with 2 plates on the upper part ; tail short, 
furnished with simple scuta. S. 156 + 30. From India ; 
