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Three-lined Boa — Part 2
As reptiles generally have suffered from the tendency to create names for "new species" upon variations of the parent form, and base "sub-species" innumerable upon slight differences of pattern the reader will at once appreciate what inspiration this genus would furnish to the enthusiastic technical worker, whose ambition it is to add to the mass of scientific nomenclature. And such has been the case. Concerning this genus a battle of nomenclature has raged. Even the well established generic name--Eutaenia, of Baird and Girard, that appeared in their excellent Catalogue of the North American Snakes, in 1853, has been declared to be inappropriate, and other generic names have been proposed, to be in turn combated. One distinguished American authority recognised nearly fifty species and subspecies of the genus. His descriptions of them were bewildering. Some of the descriptions of varieties (sub-species) were based upon single specimens. Among serpents that vary almost individually, the value of such descriptions is open to some speculation.
Foreign authorities have treated this genus from an exactly reverse attitude. Species have been run together in such strenuous fashion that but few remain to represent the genus. Thus, if the student is to examine the few technical works on reptiles, he will be confronted by these extremes, and with a very misleading result.
With this explanation the reader will appreciate the author's misgivings in preparing the present chapter. To popularise the treatment of a genus of snakes evincing extreme variability, so as to make identification simple to the beginner and valuable to the advanced student as well, is a difficult proposition. However, the task has been attempted and the student is thus advised to go about the identification of specimens:
1. Pay especial attention to form--whether stout, or very elongate, the outline of the head, and proportionate length of the tail.
2. Ascertain on what rows of scales the stripe of the side is situated.
3. Note the character of the spots (if any) between the stripes.
4. Take care to consider the locality in which the specimen was captured.
With these suggestions in mind, the student should study the key that is given herewith. From this he will gain a bird's-eye view of the genus and the distribution of the species.
It must be understood that the patterns cited in the key convey illustrations of the general run of colouration of the typical representatives of the different species and that many wide diversities of both colour and pattern occur among these snakes. Consequently the key can be nothing but a general outline of the genus Eutaenia. Those species marked with a (*From Arthur Erwin Brown, Superintendent of the Zoological Gardens, in Philadelphia, who is one of the foremost authorities on the variations of North American snakes, the writer has received many valuable suggestions regarding this genus.) exhibit phases of variation that may be very confusing to the beginner. Such variations are treated in separate keys under the heads of the respective reptiles to which they appeal, in the detailed descriptions following the key.
Only those species occurring in the United States and northern Mexico have been considered. Several species inhabit Mexico and Central America, but it is necessary that our museums should possess larger series than those now existing, before a fair estimate of the standing of these extreme southern snakes, may be given.
The key follows: (From Arthur Erwin Brown, Superintendent of the Zoological Gardens, in Philadelphia, who is one of the foremost authorities on the variations of North American snakes, the writer has received many valuable suggestions regarding this genus.)
Division A. General Pattern.--Three Yellowish Stripes on a Darker Ground-colour.
Side stripes on the third and fourth rows of scales.
a. Very slender. Tail a third or more of the total length.
Brown or black; three, vivid yellow stripes.
RIBBON SNAKE, E. saurita.