Guinea Pig
2 of the 7 encyclopedias on this shelf carry an entry for Guinea Pig. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a little animal related to the South American capybara. It is considered the type of a family midway between that of the hare and the porcupine. The name is a striking illustration of the confusion existing in popular names, for this animal is neither from Guinea nor is it in any way a pig. It has been suggested that the name may be a corruption of Guiana in South America , the region of which this animal is a native. Naturalists prefer the name of cavy. There are several wild species no one of which has the coloring of the domestic guinea pig. It was brought to Europe soon after the discovery of America, and has been a common household pet ever since. It is about eight inches in length. The guinea pig multiplies with greater rapidity than any other quadruped exceeding even the rabbit in this respect. It produces from four to twelve young when it is only two months old, and gives birth to a litter at intervals of two months thereafter. It is an exceedingly inoffensive and defenseless animal. The flesh is eaten by the Peruvians. Guinea pigs are offered like rabbits in the markets of Manila. See Hydrophobia
Collier's New Encyclopedia (1921)
the common name of the genus Cavia, family Hystricida. The common guinea pig, C. cobaia, is indigenous to South America, but is now found domesticated in all parts of the world. It has ears large and broad, the upper lip divided in two, the hair or fur erect, and somewhat resembling that of a pig. Its color is generally white, with black spots, although this is somewhat variegated by orange blotches on the coat. It has five toes on the fore legs, and three on the hind ones and has no tail. In their habits guinea pigs are extremely neat.