240 THE VIVARIUM. 
ventrals number 128 to 154, and the sub-caudals are arranged in 
from fifty-eight to eighty-two pairs, and the anal scute is divided. 
This reptile grows to a length of about 3ft. 6in., of which the 
tail measures about 94in. It is found in North America, east of 
the Rocky Mountains, and in Central America. — Its colours are 
liable to great variations, of which the following are given by Mr. 
Boulenger, viz. : 
(a) (forma typica). Brown above, with a dorsal row of 
large transverse blackish spots, and an alternating series 
of smaller spots on each side, or with dark-brown cross 
bands ; belly spotted with black or brown. Scales in 
twenty-three to twenty-five rows. 
(B) (var. sipedon). The dorsal spots as in the preceding, 
but much paler, the interspaces between them appearing 
as narrow transverse light bands margined with black ; 
belly with pale brown blotches. Scales in twenty-three 
rows. 
(c) (var. erythrogaster). Brick-red or dark-brown above, 
uniform red or copper colour beneath. Scales in twenty 
three or twenty-five rows. 
(p) (var. rhombifer). Pale brown above, with three alter- 
nating series of transverse dark brown spots, the median 
not larger than the lateral; these spots may be con- 
nected by dark-brown meshes ; belly with brown spots. 
(z) Like the preceding, but spots paler and smaller ; belly 
immaculate. 
The Mocassin Snake can sometimes be bought in this country 
for so low a sum as 7s. 6d., but generally it is much more 
expensive. 
The Tigrine Snake (7'ropidonotus tigrinus) is the representative 
of the English Ringed Snake (7. natrix) in Japan, China, and 
Siam. It is very hardy, and should be kept under the same con- 
ditions as those recommended for its near relative just mentioned. 
Some of the slight differences between this Snake and 7. natrix 
are that the former reptile has a larger eye, one more anterior 
ocular (7. natrix has nearly always only one), a squarer loreal 
(z.e., the shield between the nasal and the anterior ocular), and 
longer anterior frontals, or internasals, than the latter. According 
