It was only when, after a close examination of the sternal apparatus of one hundred and thirty species, which he carefully described, that he arrived (pp. 177-183) at the conclusion - astonishing to us who know of L'Herminier's previous results - that the sternum of birds cannot be used as a help to their classification on account of the egregious anomalies that would follow the proceeding - such anomalies, for instance, as the separation of Cypselus from Hirundo and its alliance with Trochilus, and the grouping of Hirundo and Fringilla together.
Linnaeus, even in his latest publication, placed it in the genus Hirundo; but the interleaved and annotated copies of his Systema naturae in the Linnean Society's library show the species marked for separation and insertion in the Order Grallae - Pratincola trachelia being the name by which he had meant to designate it in any future edition.
2 Linnaeus's diagnosis of his Sterna hirundo points to his having had an " arctic " tern before him; but it is certain that he did not suspect that specific appellation (already used by other writers for the " common " tern) to cover a second species.
Undoubtedly " hirundo " has now been used so indiscriminately for one species or the other as to cause confusion, which is perhaps best avoided by adopting the epithets of Naumann (Isis, 1819, pp. 1847, 1848), who, acting on and confirming the discovery of Nitzsch (who first detected the specific differences), called the southern species S.
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