THE PRINCIPAL SPECIES OF POISONOUS SNAKES 27 
capable of finding their own food. Their length at birth amounts 
to 230 millimetres. 
The two glands of an adult adder contain about 10 centigrammes 
of poison. ‘This smail quantity is sometimes sufficient to cause 
death ; out of 610 persons bitten, Rollinger returns 59 deaths, or 
about 10 per cent. 
In the departments of Vendée and Loire-Inferieure alone, Viaud 
Grand Marais has noted during a period of six years 321 cases of 
bites from adders, 62 of which were followed by death. In 
Auvergne, Dr. Fredet! (of Royat) returns 14 cases, which caused 6 
deaths. 
Vipera aspis (Asp, or Red Viper). 
(Fig. 21, 2, and fig. 22.) 
Snout slightly turned up, soft and squarely truncate ; vertical 
diameter of the eyes equal to the space separating them from the 
mouth; upper surface of the head usually covered with small, 
imbricate, smooth or feebly keeled scales, in 4—7 series, between 
the supraocular shields, which are prominent. The frontal and 
parietal shields are usually wanting ; sometimes they are distinct, 
but small and irregular; the former are separated from the supra- 
oculars by two series of scales; 8—13 scales round the eyes; two 
(rarely three) series of scales between the eyes and the labials ; 
nasal shield single, separated from the rostral by a naso-rostral 
shield. Body scales in 21—23 rows, strongly keeled; 134—158 
ventrals ; 32—49 subcaudals. 
Coloration very variable, grey, yellowish, brown, or red above, 
with a zigzag band as in V. berus. Usually a black U-shaped 
mark on the hinder part of the head, with a longitudinal black 
streak behind the eyes; upper lip white, or yellowish. Ventral 
surface yellow, white, grey, or black, with lighter or darker markings. 
Total length, 620—675 millimetres ; tail 75—95. 
l Acad. de médecine, March 19, 1889. 
