This name occurs in several of the older authors on American Natural History, which is to be attributed to the fact that the _Whip-poor-will_ (_Antrostomus vociferus_) was regarded by Linnæus as a variety only of the European Goatsucker. President Jefferson, in Notes on the State of Virginia, p. 117 (London edition, 1787), gives both of the then known North American birds of this group as two varieties only of the European bird. Professor Barton, in Fragments of the Natural History of Pennsylvania, p. 14, under the head of _Caprimulgus europæus_, says: “This, or a variety of it, is certainly a native of Pennsylvania. So that now all the fifteen species of this genus (mentioned by Gmelin) are known to be natives of America.” Both of these distinguished and venerated fathers of American zoological science adopted the opinion of Linnæus, and the name of the European bird is given also on the same authority by some others of the earlier American writers. The European Goatsucker has never been observed on the continent of America. Professor Barton’s observation above quoted is singularly suggestive. Linnæus, at the date of his last edition of the Systema Naturæ, knew _two_ species only of the genus _Caprimulgus_. Gmelin, in the edition of the same work, edited by him, and published in 1788, extended the list to _fifteen_ species, and was, when Professor Barton wrote, in 1799, recent and high authority. So greatly has the knowledge of species of birds been extended, that at this time (1855) there are at least ninety known birds of the family _Caprimulgidæ_, all of which would have been regarded by Linnæus and Gmelin as belonging to the genus _Caprimulgus_. There are seventy-four species of this family in the collection of the Philadelphia Academy. Though, as Professor Barton observes, all of those known to Gmelin (except _Caprimulgus europæus_), are American, others are now ascertained to inhabit all the temperate and tropical regions of both of the great divisions of the globe, and the whole of Australia.