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Show 1873.] SIR V. BROOKE ON THE GENUS GAZELLA. 535 conjunction with other differences, for the entire separation of this family from the other Accipitres, then the above mentioned group of families seems a natural one*; but if the Strigidae are intimately related to the Falconidae and Vulturidae, it is so difficult to believe that the Coraciidae and their allies are related to the Falconidae, that the entire separation of the Strigidae from the Caprimulgidae seems essential, in which case the position of Steatornis becomes more doubtful. 2. On the Antelopes of the Genus Gazella, and their Distribution. By Sir V I C T O R B R O O K E , Bart., F.Z.S. (Plates XLV. & XLVI.) Whilst at Berlin last year I noticed in the gallery of the Royal Museum a large Gazelle (No. 3207 in the Catalogue), which struck me as being different from any thing I had before seen. Upon mentioning the specimen, which was unnamed, to Professor Peters, he informed me that it had been brought from the far south of Senaar by Casanova, but that, being unable to refer the specimen to any described species, he had preferred to leave it unnamed rather than to run the risk of giving it a specific title in the absence of a sufficiency of materials to establish its right to this distinction. Observing my interest in the matter, Professor Peters with great generosity handed the investigation of it over to me, requesting me to describe the species in the Society's ' Proceedings' should I come to the conclusion that it was unknown and new. This, so far as I have been able to make out, is not the case, the Antilope melanura described by Heuglin (Antilopen und Biiffel, p. 6) agreeing very exactly with the Berlin specimen. The matter, however, is not the less interesting; and as the species is at present only known by Heuglin's short description, and appears to be represented in European museums solely by this specimen, I have thought it desirable to describe it more fully. At the same time the very scattered and fragmentary condition of our knowledge of the entire group Gazella has induced me to take this opportunity of passing in review the various persistent modifications of the form which have been deemed by former authors worthy of specific distinction. Although I have retained in an equality as to specific rank all the modifications mentioned in the following list, yet I am desirous of stating that I only do so from absolute inability to do otherwise without introducing complications into the list, which would, I fear, militate against its practical usefulness. The laws of variation and persistent modification are at present so imperfectly understood that it is difficult, if not impossible, to connect terms of value with the phenomena of differentiation-terms which shall be sufficiently definite to express what we know and are sure of, and yet sufficiently plastic to meet the requirements of future research. The principle which suggested the term " persistent modification " to * Prof. Newton has for some time believed the Steatornithida? and Caprimulgidse to be distinct families (cf. Zool. Rec. vi. p. 67). |