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Show 170 MR. W. A. FORBES ON THE GENUS LATHAMUS. [Feb. 18, tract is observable, tbe inclosed space being of about the same as either of the tracts inclosing it, no tendency to a dilatation of tbe arms at their junction (though there is some in front) being present, and the rows of feathers in front having a more or less clear 3.1.3 arrangement. The lumbar feathering is always very weak; so that the boundaries of the dorso-lumbar fork are very clearly defined. Lathamus, however, differs from the above-mentioned forms a little by its longer and not so widely divaricated scapular fork, and by the greater breadth of its inferior tract on the sternum, thereby causing a corresponding diminution in the breadth of the carinal space. The general agreement, however, of the pterylosis in the two types will, I think, at once be evident from the figure of Lathamus (PI. X V I . figs. 1, 2), and that of Platycercus pennantii (PI. XVI. figs. 3, 4), which I have represented next to it for the sake of comparison. If now we turn to the Trichoglossince1 (See PI. XVI. figs. 5, 6), in which so many naturalists have included Lathamus,we shall find important and well-marked differences in the two tracts mentioned above, though the general character of the pterylosis remains the same in all2. The outer pectoral tract is never so narrow and distinct here as it is in Lathamus and its allies ; it is usually almost triangular in shape, and so tolerably broad, shorter, and not so divergent, the interspace between it and the main tract being much narrower, and frequently with a few scattered feathers in it uniting the two tracts together. The inferior tract on the breast is always much broader, and the carinal space narrower. Still better-marked characters between the two groups are to be seen in the disposition of the dorso-lumbar fork. This in all the Trichoglossince is extremely weak in front, the tracts not getting at all strongly feathered till some way (in T. concinnus | inch) from the ends of the scapular fork. Each arm is much shorter (in all the forms I count about eight rows of feathers to the junction), wider and more diffusely feathered than in the Platycercinee, and becomes dilated and more strongly feathered towards its junction with its fellow, which takes place further from the tail than in the other group. The united tract is strongly feathered and rather broad at first, but narrows rapidly again towards the tail. Figs. 5 and 6, PI. XVI. represent the pterylosis of Trichoglossus concinnus (a bird a little larger than the "Swift Parrakeet"), and show the differences between the two groups, which, if somewhat slight, are nevertheless easily appreciable after a little study, and are as well marked as any others I have as yet observed in the pterylosis of this order. Several points in the external characters of Lathamus show that 1 Of these I have examined the pterylosis in Eos rubra, Trichoglossi ornatus, hcematodes, swainsoni, concinnus (two specimens), and pusillus, and Coriphilus fringillaceus. 2 I have as yet been unable to confirm Nitzsch's observation (Pterylogr. Eng. edit. p. 100) that in Lorius garrulus and L. domicella the inferior tracts are continuous over the lower surface of the neck. |