OCR Text |
Show 172 MR. W. A. FORBES ON THE GENUS LATHAMUS. [Feb. 18, it has in fact no particular relationship to the Trichoglossince. shape of the upper mandible, with a small but distinct tooth, is obviously (see fig. 1, p. 171) much nearer to that of Psephotus (fig. 3) than it is to that of a Lory (fig. 5). The same story is told still more plainly by its maxilla, which has none of the laterally compressed, elongate, and pointed form characteristic of the Lories, and which induced Sundevall to divide all Parrots into two groups " Psittaci proprii" and "Psittaci orthognathi," the latter including only the Lories and Nestor, and characterized by having the " maxilla inferior recta, angusta, altitudine longior." In Lathamus the maxilla is short and deep, with a broad and rounded anterior margin. These differences will be seen by a glance at figures 5 and 1, representing the heads of a Trichoglossus (concinnus) and of Lathamus. In all the Trichoglossince I bave examined, the cere is rather narrow from before backwards, the anterior margin only sinuate, and the nostrils elongated and ovate, with their long axis directed forwards and inwards, and so somewhat transversely to the direction of the beak (fig. 5, p. 171). This is very evident in the living birds, and is also to be made out in skins. In Lathamus, however, and the Platy-cercinee generally, the cere is much larger, with the anterior border on each side nearly semicircular; and the nostrils are oval and directed upwards, more nearly parallel with the culmen (see figs. 1 and 3). In the small size of the nude orbital ring Lathamus agrees with the Platycercinee rather than with the Lories, in which it is of fair size and rather conspicuous in the living birds. In the shape of the wings, no doubt, Lathamus is somewhat aberrant, and nearer the Lories than the Platycerci. This is, however, so obviously an adaptive modification, due to the swift flight and arboreal habits of both these birds as compared with the more ground-loving mode of life of the Platycerci, that no stress can be laid on it as a taxonomic character. The rounded end of the wing-feathers, however, of Lathamus still point to its Platycercine affinities. Its feet, too, though not typically Platycercine, differ from those of the Trichoglossince (cf. figs. 2 and 6, p. 171) by their more elongated and slender tarsi and toes, with the latter not so much flattened and fitted for grasping branches, & c , as are those of the Lories, and with the claws not so strong and longer, particularly that on the third digit. In both these points more resemblance to the Platycerci is shown (cf. fig. 4, p. 171, foot of Psephotus heematogaster), though the different modes of life * have here again induced a certain amount of change from the form observed in the truly terrestrial Platycerci. A thorough study of the osteology of the Parrots has yet to be 1 Mr. Gould says (' Handb. B. Austr.' ii. p. 89):-" In its actions and manners it is closely allied to the Trichoglossi, but differs from them in some few particulars, which are more perceptible in captivity than in a state of nature. It has neither the musky smell nor the jumping motions of the Trichoglossi. I have never observed it alight on the ground, or elsewhere than among the branches." |