172 
OIT THE PHYSIOaNOMY OF SERPENTS. 
by five series of spots in a qiiicnnx ; tail lengthened in 
proportion to the dimensions of the trunk. S. 117 + 73. 
Country unknown. 
14. Homalopsis Herpeton. — An entirely anomalous 
species, and one of the most remarkable of serpents for two 
fleshy appendages, which proceed from the point of the 
snout, and are covered with scales. Abdominal plates 
scarcely exceed in breadth the scales, and each is sur- 
mounted by two keels ; 35 rows of scales strongly cari- 
nated. Habit, size, and form of H. Schneideri, but the 
trunk is very thick in the middle ; the head covered with 
small scales, and on the crown by 9 plates, among which 
we may observe several scales of an irregular form. Teeth 
of equal length. S. 140 + 96. Brown, rayed with a light 
colour. Country unknown. 
I have included the Boas in the sixth family oi innocu- 
ous serpents. They have a prehensile tail, and also the 
faculty of entwining themselves round any object with 
their trunk. Their scales are numerous, and the plates 
on the lower parts are very little developed. The head is 
thick, with strong features, and covered with scales, or with 
small plates, of which the form and disposition are very 
dissimilar ; they eyes are small, and usually have a pupil 
horizontally elongated ; the nostrils are more or less ver- 
tical ; the labial plates are often hollowed out by several 
fossettes ; the lung is usually divided into two lobes, and 
there is a hook at the anus. The species inhabit the warm 
regions of both worlds ; they are not numerous, and most 
of them surpass all other snakes in their dimensions. Se- 
veral species frequent fresh water ; others inhabit forests ; 
and there are some of them essentially aquatic. They 
have the habit of crushing their prey in the folds of their 
bodies, and of breaking its bones before swallowing it. 
This family divides itself into three generic groups. 
BOA. 
The first genus is the jSoa, properly so called. In^this 
species the intermaxillary bone is unprovided with teeth, 
