Boa Constrictor
2 of the 6 encyclopedias on this shelf carry an entry for Boa Constrictor. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a huge tropical serpent closely related to the python and the anaconda. It is about half as large as a python. It attains a maximum length of twelve feet. It is found in the forests of South America from the Caribbean Sea to Paraguay. An interesting anatomical feature is a vestige of a pair of hind legs in the form of a pair of claws, situated about where the hind legs of a lizard are found. These claws are of assistance in clinging to the branch of a tree. The boa is noted for having 305 vertebrae. The frog has but ten. The boa constrictor is not poisonous. It is a land serpent. It feeds on monkeys, young peccaries, tapirs, agoutis, and the larger birds. It seizes its prey with lightning-like rapidity, and, holding on with its teeth, throws coils of its body about its victim so as to strangle it. The name constrictor has reference to this habit of crushing its food. When all movement has ceased, the boa relaxes, comes at its feast head first, covers it with saliva, drops its lower jaw out of joint, and gorges its food whole. In the stupid condition which follows, the boa may be attacked with impunity; but woe betide the adventurous monkey that comes too near under ordinary conditions! The boa is large enough, no doubt, to crush a man or a horse, but there is no recorded instance of its having killed either. It is not large enough to swallow a man. See Python ; Anaconda
Collier's New Encyclopedia (1921)
the best known name constrictor, meaning binder or drawer together, refers to the method through which the animal destroys its by itself round it and gradually tightening the folds. It is about 30 feet long. It is found in South America.
What Has Changed in the Last Century
The two accounts could not agree on size: Aiton's in 1910 gave a maximum of twelve feet, Collier's in 1921 said "about 30 feet long." Aiton's was much nearer the mark — boa constrictors typically reach about 6 to 10 feet, with the largest reliable specimens around 13 feet; the 30-foot figure belongs to the reticulated python and green anaconda, not the boa. The old description of the kill as strangling or crushing has also been overturned: experiments published in 2015 showed that constriction kills chiefly by shutting down blood circulation, causing cardiac arrest within seconds, rather than by suffocation or broken bones. Modern herpetology also splits the animal, treating the Central American and Mexican populations as a separate species, Boa imperator, and the snake has established a breeding foothold in southern Florida far from the South American forests both entries describe.
Written for this edition, 2026.