. La struttura e la classificazione degli uccelli . ramo. Questo presto termi-nates, ma i rami interni sono continu.ed fino a thecloaca. L'apteia essendo interamente priva di piume giù, i tratti sono facilmente definiti, ma nonostante questo Nitzschhas, a mio parere, caduto in alcuni errori. La disposizione tipica della pterilosi dorsale ^(mostrata in fig. 91) può essere considerata quella di MegaleBma e si è trovato caratterizzare le specie M. asiatica, M.virens, M. Hodgsoni, M. javensis, M. Franhlini. Lo spinaltract è singolo e stretto sul collo, lasciando così con- 1 CREEBEii, Pterylose v
1730 x 1444 px | 29,3 x 24,5 cm | 11,5 x 9,6 inches | 150dpi
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. The structure and classification of birds . branch. This soon termi-nates, but the inner branches are continu.ed as far as thecloaca. The apteiia being entirely devoid of down feathers, the tracts are easily defined, but in spite of this Nitzschhas, in my opinion, fallen into some errors. The typical arrangement of the dorsal pterylosis ^(shown in fig. 91) may be considered to be that of MegaleBma^and was found to characterise the species M. asiatica, M.virens, M. Hodgsoni, M. javensis, M. Franhlini. The spinaltract is single and narrow upon the neck, thus leaving con- 1 CrEEBEii, Pterylose von Tetragonops, Zeitsehr. f. d. ges. Naturw. li. 1878, p. 377. 2 On the Pterylosis of Certain Barbets and Toucans, P. Z. S., 1896, p. 535. PIOI 193 spicuous lateral neck spaces; behind the scapulae it forks, and the posterior part of the spinal tract is not in continuitywith the interior. The former is at first a single tract, butit divides some way in front of the oil gland, which itsurrounds, as in the Picidse and Ehamphastidae ; but in the. Fig. 91.—Feather Tkacts or Megalisma asiatica. The Eiohi-hani) FiGDBE SHOWS the VeNTEAL SuBFACE, THE LeFT THE DOBSAL. former family there is also a median continuation of thespinal tract, which stops at the base of the oil gland. Oneach side of the spinal tract is a very narrow lateral tract, which is figured by Nitzsch as existing also in the Eham-phastidae and the Picidae. Xantholcema rosea shows differ-ences from Megalama ; the spinal tract divides in the usualway, but the tracts rejoin, so as to enclose a diamond-shapedspace ; they then again diverge immediately, and end at thesides of the oil gland in the usual way. Xantholmma has a faint lateral tract on either side. Inspite of Nitzschs figures I am disposed to think that thistract, so universal in the barbets, is at most feeble in thetoucans. In the continuity of the anterior and posterior 0 194 STEUCTUKE AND CLASSIFICATION OF BIRDS parts of the spinal tract Xantholama is more touca
