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Show 1899.] ON THE CRANIAL OSTEOLOGY OF THE PARROTS. 9 During my various changes of venue I accumulated a rich material of Enteropneusta, au account of which I shall shortly publish in Part III. of m y Zoological Results which are being issued by the Cambridge University Press. Lastly, it was m y happiness to discover a new type of Peripatus in N e w Britain which differs from the South African, Australasian, and Neotropical subgenera in the same respects-anatomy and development-in which they differ from one another. It constitutes therefore a fourth subgenus, which I have called Paraperi* patus. With regard to Peripatus, the next point of interest centres upon the new species-P. tholloni, which has recently been described by Mons. E. L. Bouvier from the Gaboon district (West Africa). 2. On Characteristic Points in the Cranial Osteology of the Parrots. By D ' A R C Y W . T H O M P S O N , C.B., F.Z.S. [Received November 16, 1898.] To discover anatomical characters such as might yield or help to yield a natural classification of the Parrots has been the desire of many ornithologists, but the search has availed little. Garrod's abundant w^ork has told us many facts in regard to the presence or absence of an ambiens, of an oil-gland, of one carotid or two, and other varying characters in a multitude of species ; but when we come to put these data together the result is unsatisfactory, and one is left with the impression that the several series of facts are incoordinate and cannot be linked together in a single system. W h e n we find, for instance, that the collation of these facts places in a single group Ara, Psittacus, Pyocephalus, and Nestor, and in another Stringops, Melopsittacus, and Agapomis, one is tempted to think that the only thing proved is that the data are invalid or antagonistic-in other words, that the several structures had really followed diverse or parallel or convergent lines of modification and evolution. While such internal structures seem to m e to lead to confusion by indiscriminate variability, the characters of the skeleton are generally deemed too monotonously alike to present features of significance. Even in Stringops, the osteological peculiarities of which are greater than those of any other form (except perhaps Nestor), they are yet not conspicuous enough to have prevented certain recent writers from remarking that the divergence of Stringopjs from the other Parrots is not so great as it had been supposed to be. There is indeed in most parts of the skeleton a very great uniformity throughout the order, but in certain parts, for instance the orbital ring (where the differences are well known, though imperfectly investigated)l, the hyoid bone (as Dr. St. G. Mivart has 1 Cf Em Blancbard, " Oaracteres osteol. cbez les Ois. de la famille des Psittacides," C. R. xliii. pp. 1097-1100 (1856), xliv. pp. 518-521 (1857); 0. L. Bonaparte, ibid. xliv. pp. 534-539 (1857). |
