The word viper is interesting; coming directly from the Romans, who wrote it _vipera_. This in turn is a contraction of the feminine form of the adjective _vivipera_, in reference to the habit of these snakes of bringing forth their young alive.
Lizard, through such forms as _lesarde_, _lezard_, _lagarto_, _lacerto_, is from the Latin _lacertus_, a lizard; while closely related is the word alligator by way of _lagarto_, _aligarto_, to alligator. The prefix may have arisen as a corruption of an article and a noun, as in the modern Spanish _el lagarto_,--a lizard.
Monitor is Latin for one who reminds, these lizards being so called because they are supposed to give warning of the approach of crocodiles. Asp can be carried back to the _aspis_ of the Romans, no trace being found in the dim vistas of preceding tongues.
Gecko, the name of certain wall-hunting lizards, is derived from their croaking cry; while iguana is a Spanish name taken from the old native Haytian appellation _biuana_.
Of the word frog we know nothing, although through the medium of many languages it has had as thorough an evolution as in its physical life. We must also admit our ignorance in regard to toad, backward search revealing only _tade_, _tode_, _ted_, _toode_, and _tadie_, the root baffling all study. Polliwog and tadpole are delightfully easy. Old forms of polliwog are _pollywig_, _polewiggle_, and _pollwiggle_. This last gives us the clew to our spelling--_pollwiggle_, which, reversed and interpreted in a modern way, is wigglehead, a most appropriate name for these lively little black fellows. Tadpole is somewhat similar; toad-pole, or toad's-head, also very apt when we think of these small-bodied larval forms.
Salamander, which is a Greek word of Eastern origin, was applied in the earliest times to a lizard considered to have the power of extinguishing fire. Newt has a strange history; originating in a wrong division of two words, "_an ewte_," the latter being derived from _eft_, which is far more correct than newt, though in use now in only a few places. Few fishermen have ever thought of the interesting derivation of the names which they know so well. Of course there are a host of fishes named from a fancied resemblance to familiar terrestrial animals or other things; such as the catfish, and those named after the dog, hog, horse, cow, trunk, devil, angel, sun, and moon.