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Show 270 MR. FORBES ON THE PTERYLOSIS OF MESITES. [Feb. 21, The third patch is inferior in position, lying just at the commencement of the pectoral region, between the two halves of the inferior tract internally and the anterior extremity of their separated pectoral branch externally. The fourth patch is longer and narrower than its fellows, lying on the ventral region just outside the middle part of the inferior tract. The fifth (lateral) patch lies more or less transversely, in the neighbourhood of the axilla, between the posterior ends of the outer pectoral and humeral tracts. N o Ardeine bird has any such lateral pair of patches; and only Cancroma has the anterior dorsal pair. These moreover lie outside, and not inside, the dorsal tracts in that bird. On the other hand, the concentrated patches of Mesites m a y easily be derived from the more diffused arrangement found in Rhinochetus1 and Eurypyga. A full account of the pterylosis of Rhinochetus is still a desideratum, Dr. Murie having unfortunately omitted any account of the systematically more-important contour-feather tracts in his account of the " dermal structures " of the Kagu (/. c). I have at present insufficient material to describe these thoroughly, though an examination of two imperfectly-feathered specimens in spirit demonstrates considerable agreement between the Kagu and Mesites. Of Eurypyya we likewise have but imperfect information, due to Nitzsch2, and not to m y mind very satisfactory, judging from the material before me. In Rhinochetus, as in Mesites, the neck-feathering is quadriserial, though the median dorsal space is m u c h narrower below and the lateral neck-spaces very broad ; the two dorsal tracts terminate close together about the level of the anterior end of the scapula?, and are quite separate from the posterior portion, which is only forked to a slight extent anteriorly, and widely dilated mesially. These differences seem to be due mainly to the greater development of the dorsal powder-down tracts of Rhinochetus, these covering most of the dorsal aspect of the trunk, except a narrow median space along the backbone and a reversed heart-shaped area on the pelvis, to which spaces therefore the contour-feathers are nearly confined. Below, as in Mesites, the inferior tract of each side is nearly or quite broken up into two by the interruption of a patch of powder-down feathers ; and the pectoral branch is likewise quite separated from the main tract, as in no other bird known to m e except Mesites, powder-downs also intervening between the two. The humeral tract is quite free from the inferior one. On the other hand, in the number of its rectrices (16), and the absence of an aftershaft to the feathers, Mesites differs from Eurypyga and Rhinochetus, both of which have 12 rectrices3 and an aftershaft. The number of primaries in all is 10. Mesites, Rhinochetus, and Eurypyga agree together, but differ from the Rallida, in having well-developed and strong rectrices, in 1 Cf. Murie, Trans. Z. S. vii. pl. 56. figs. 1-3. 3 ' Pterylography,' Kay Soc. eel. p. 129, pl. viii. fig. 15. 3 Rhinochetus has not 10, as erroneously stated by Murie, loc. cit. p. 468 |