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Show 174 MR. W. A. FORBES ON THE GENUS LATHAMUS. [Feb. 18, pelvis is wider, the preacetabular part much shorter, and the iliac fossae shallower and smaller. These differences will be visible from the figures which I exhibit (PI. XVI. figs. 11, 12), in which are shown respectively the pelvis of Lathamus and of Lorius tricolor. As regards internal anatomy, little can be said of any important characters, except the difference in the disposition of the carotid arteries in the two groups, first pointed out by Prof. Garrod, and already mentioned above. The nature of the tongue in Lathamus requires reexamination, as also does the coloration of the eyes, this presenting very marked characteristics in all those Trichoglossince I have been able to examine alive (of the genera Lorius, Eos, Chalco-psitta, and Trichoglossus), and being quite unlike that prevalent in the Platycerci and most other Parrots. In coloration Lathamus is no doubt aberrant, but is no more clearly related, as far as I can see, to one group rather than the other. The external rectrices being blue is perhaps a hint of its Platycercine relations. To conclude, the more important characters of Lathamus, i. e. pterylosis and superficial left carotid, beak, nostrils, cere, feet, skull, and pelvis, all point to a near relationship to Psephotus, Platycercus, and allied genera. The abnormal tufted tongue, the retention of the furcula, and the sharp pointed wings may be regarded as adaptations to its tree- and flower-loving modes of life, and not as due to any consanguinity with the Trichoglossince. Lathamus may be a more or less modified remnant of a group that branched off from the common stock with the progenitors of the more typical Platycerci, and of which all the others have become extinct (perhaps due to the competition with the more specialized Trichoglossince) ; or it may be a member of the Platycercine group that has become specialized to modes of life like those of the true Lories and Lorikeets, and so has come to resemble them in some few superficial particulars. EXPLANATION OF PLATE XVI. Figs. 1, 2. Back and side views of Lathamus discolor, showing pterylosis. 3, 4. The same of Platycercus pennantii. 5, 6, The same of Trichoglossus concinnus. 7. Mandible, deprived of horny sheath, of Eos rubra. 8. The same of Lathamus discolor. 9. Skull, seen from above, of Eos rubra. 10. The same of Lathamus discolor. 11. Pelvis of Lorius tricolor. 12. The same of Lathamus discolor. |