IN a lecture on ‘Chameleons’ at the Zoological Gardens, Professor St. George Mivart described in his peculiarly lucid, facile manner, some of the features possessed in common by totally different zoological families, and facetiously added, ‘It is tiresome how a single species will come and interfere with our nice definitions in classification.’[116] I will devote a chapter to the confusion arising from some such mixed features. In the classification of the Ophidia these tiresome complications present themselves more, perhaps, than in any other creatures. We have seen how snakes of entirely opposite families may possess one single feature in common and differ in other generic respects; as, for instance, in the moveable but innocuous fang of the _Xenodons_; in those ‘pits’ or depressions in the face; the viperine form of head; the position and number of head-shields; the sub-caudal plates, and so on; and in such resemblances I am strongly inclined to suspect that there are other interfering causes than a common ancestry, though this, no doubt, has much to do with it. ‘What is to prevent our having one fixed name, and keeping to it?’ exclaim the sorely-puzzled amateur naturalists. And well they may, on seeing in some works on ophiology a list of synonyms sometimes filling several pages. By way of illustration let us take the little spine-toothed snake described among the egg-eaters in chap. iii. This snake was known to be _edentulus_ by Linnæus, who nevertheless gave it the generic name of _Coluber_, because it has two rows of sub-caudal plates; and the specific _scaber_, because it has roughly-carinated scales—both names equally applicable to a score of other snakes, and not at all describing its unique dentition. This latter was first made a distinguishing feature by Jourdan, 1833, who assigned it the generic name of _Rachiodon_, spine-toothed. Lacepède called it simply _La rude_; Wagler, _Dasypeltis_, thick or rough-scaled, the integument rather than the dentition still receiving prior attention by the majority of observers.