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Show 246 EXPLOrATION OF THE CANONS OF THE COLORADO. giving compiled indications only of several others. Woodhouse described a new species in 1853. Various naturalists of the Pacific Railroad Surveys furnished field-notes of observation, but their determinations, to state a well-known fact, were not upon their own authority. In fact, the literature of the whole subject, so far as original work in determination of species is concerned, focuses only in two authors-Richardson, 1829, and Baird, 1857. No species of Thomomys having apparently been described before 1829, the history of the genus may be considered to begin at that date. The eminent author of the Fauna Boreali-Americana gave five species of "Geomys" and "Diplostoma.'' One of these is a true Geomys; the four remaining ones (douglasii, bulbivorum, talpoides, and umbrinus), to which a fifth (borealis) was subsequently added, are all Thomomys. These accounts of Richardson's remained for many years the principal, and, in some cases, the whole, source of what has been written upon the determination of species; and they include every form of the genus known up to this date (every subsequent name proposed having proven a synonym). I hardly know where to look for the parallel of this curious case. Two points strike one in reviewing Richardson's work: First, he had a wholly erroneous idea that there were two distinct genera, "Geomys" and "Diplostoma," in one of which the pouches, opening into the mouth, dangled naturally as sacks on each side, and in the other of which the pouches were as we know them to be. This radically wrong premise vitiated all his work, and led him to the length of describing one and the same species as "Geomys douglasii" and "Diplostoma bulbivorum.'r Secondly, the minute descriptions consist mainly of the repetition, under varying forms of expression, of generic characters, common, of course, to all the species. When sifted of their generalities, there is very little left; though, fortunately, such was this author's habitual accuracy, the residuum suffices, when coupled with the indications of locality, for the identification of all his species. As already stated, there was little real change in the state of the case from 1829 to 1857, when Professor Baird reviewed the subject, with considerably more material and much more other information than Richardson appears to have possessed. " Diplostoma" had meanwhile been effectually disposed of; but to this author is due the credit of having first actually identified with specimens several of Richardson's species, which, though often |
