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Show 1879.] MR. P. L. SCLATER ON CERTAIN PARROTS. 299 unknown cause at an unusually early age in the males, and their consequent transference to both sexes." ' That sexual selection has played a very important part in the subsequent development of tbe horns and antlers of the Pecora there can be no reasonable doubt; but the known facts appear to m e to indicate that they were probably first developed in both sexes as organs of defence against common enemies. They are present in the females of the Camelopardalidce, in those of all the Bovidee except twelve genera of Antilopince2, and in those of one genus of the least-specialized section of the Cervidce, while we have seen that they are not unfrequently abnormally developed in the two other genera of the same section with which we are best acquainted. The same abnormality, it may be added, occurs in at least one of the genera of Antelopes, in which the females are usually hornless3. On the assumption that the antlers and horns of the Pecora were first developed in the males only, their presence in the females of so many forms can only be explained by the hypothesis that " an unknown cause" has led to their transference from the other sex. On the other hand, if they were at first common to both male and female, the problem appears to me to be capable of a more satisfactory solution. In the males they would naturally be further developed by sexual selection, and in the females the strain on the constitution would tend to their reduction or even elimination - this strain, as Mr. Darwin himself has pointed out, being much the greatest in the Cervidce, in which the weapons require to be renewed every year. That they should be retained (usually in reduced size) by the females of most of the forms with non-deciduous horns appears therefore to be natural; while their retention in the female of the Reindeer, and their occasional abnormal development in those of other little-specialized Deer, is no more than we should expect on the doctrine of heredity. 3. Remarks on some Parrots living in the Society's Gardens. By P. L. S C L A T E R , M.A., Ph.D., F.R.S., Secretary to the Society. [Received March 13, 1879.] (Plate XXVIII.) During the preparation of a new edition of the List of Vertebrates in the Society's Collection I have, as on former occasions of a like nature4, made several notes referring to special rarities and necessary charges in nomenclature of the Psittacidse, which I beg leave to offer to the Society. Our series of Psittacidse at the present moment consists of about 170 individuals, belonging to 98 species, amongst which, besides those i Tom. cit. p. 504. 2 Sir V. Brooke, P. Z. S. 1878, p. 884. 3 Blyth as quoted by Mr. Darwin, ' Descent of Man,' p. 505. * Cf. P. Z. S. 1867, p. 183, et 1871, p. 493. |