98 ON* THE PHYSIOaKOMY OF SERPENTS. 
We must reckon in the first rank of all known serpents, in 
respect to its dimensions, the Boa murina, a native of the 
equatorial regions of America. The Python bivittatus, 
spread over intertropical Africa and Asia, is in the ancient 
continent the representative of that Boa, and attains nearly 
the same size. It is now found that the Python Schneideri, 
inhabiting India, has an elongated shape, and rarely sur- 
passes fifteen feet in total length ; the Boa Constrictor of 
the New World joins to an inferior length a very consider- 
able thickness ; as also do several other Boas, Colubri, &c. 
In our climate, serpents are rarely more than five feet in 
length, but in middle Europe there is one species of Colu- 
ber which arrives at the length of eight feet.^ 
HABITUDES. 
Ophidians are spread over every country where the 
conditions necessary to the existence of reptiles in general 
are found. Every person knows that these cold-blooded 
animals love heat ; that their number diminishes for this 
reason in proportion as we approach temperate or frigid 
regions ; and that they prefer, on that same account, banks 
exposed to the heat of the sun, to elevated situations, or 
places covered with a thick and abundant vegetation. Yet 
there are, even with us, species common in the plains, which 
at the same time frequent the slopes of mountains, even at 
the height of several thousand feet above the level of the 
sea. Many Tropidonoti in Java abound on the solitary 
peaks of the numerous extinct volcanoes, with which that 
island is bristled. But by far the greatest number of 
Ophidians inhabit low lands, either naked or bosky, dry or 
humid, and marshy. Some are only seen in the vast sandy 
plains of the old continent ; the analogous deserts of both 
Americas, known under the names of Pampas, Llanos^ or 
Savanas, are peopled by other species, often spread over 
a vast extent of that continent. A great number of ser- 
pents frequent shady places, and often even occur in the 
thickest forests, sometimes concealedunder luxuriant herbage 
Coluber quaterradiatus, the Boa of the ancient Romans. 
