Page:The Zoologist, 3rd series, vol 1 (1877).djvu/242

216 confusing subdivisions. First, Wagler took the MS. description, or perhaps even the type specimen, of J.R. Forster's Sterna serrata, which he identified, and correctly, with S. fuliginosa, but as that individual specimen had a claw somewhat notched and jagged from contact with rocks, he formed for its reception the genus Onychoprion (Isis, 1832, p. 277 ), from ὅνυξ, nail, πρίων, a saw. He then took another of Forster's types, named in his MS. Sterna guttata, which this time happened to be an example of S. fuliginosa, in which the accidental serration above referred to was not observable: here it seemed to him was another structural (!) difference, on which he accordingly based the genus Planetis (Isis, 1832, p. 1222 ), from πλάνητός, wandering. Not yet satisfied, he took a third specimen of S. fuliginosa, and, almost on the same page, gave it generic distinction under the name of Haliplana (Isis, 1832, p. 1224 ), from άλίπλανος, sea-wandering. That was pretty well for one systematist's work with a single species: others have placed the same bird in two other genera besides Sterna, but let that pass.

With regard to the propriety of separating the Sooty Terns generically from the other Sea Terns, I would remark that I can find no structural difference in the former, their only peculiarity consisting in their coloration,—a distinction insufficient in my opinion for the formation of a genus,—and even in that respect there is a species found at Alaska, Sterna aleutica, which, with head markings and mantle similar to those of S. fuliginosa, has a while rump and tail, thus forming a connecting link. But although there is no well-defined structural difference between S. fuliginosa and the typical Sea Terns, there actually exists a real noticeable structural variation in the formation of the feet of such closely allied-species as S. fuliginosa and S. anæstheta—forms which the most persistent genus-maker would hardly venture to place in different genera—yet it is clearly shown that they differ more markedly inter se than they do from typical Sterna.

Under these circumstances, I would submit it to the judgment of ornithologists whether it is not advisable to disregard Wagler's genera, and to retain the Sooty Terns in the genus Sterna.