1882. ] PTERYLOSIS OF MESITES. 269 
being of a furcate form, with the united part about 1 inch long, and 
inclosing a fairly broad median space. The limbs of this posterior 
fork are strongly dilated in the middle part of their extent, being there 
6 to 7 feathers broad, and united externally by scattered feathers with 
the very broad and long lumbar tracts, which are arranged in about 
six rows of not closely-placed feathers, the posterior row of these 
being considerably the stronger. 
The humeral tracts are not very broad or strong, and are quite 
distinct, anteriorly, from the inferior tract. 
This last, which (as already described) commences on each side 
about halfway down the neck, springing at once independently 
from the continuous feathering of the anterior cervical region, 
ceases altogether at the commencement of the pectoral region 
(extending as far as the most anterior of the ventral powder-down 
patches to be presently described). It recommences, however, a little 
lower down as a very narrow tract, composed at first of only single 
feathers, but subsequently becoming stronger and broader (though 
even here only two feathers broad), in which condition it runs on, as 
the main inferior tract, to terminate near the vent. 
Strange to say, what must be considered the equivalent of the 
outer pectoral branch of ordinary birds is here quite free throughout 
from the main stem, with which it is not even united anteriorly, 
where it is separated by the already-mentioned powder-down patch, 
whilst posteriorly it runs parallel to, but quite free from, the main 
stem. 
The powder-down patches of Mesites resemble those of the 
Ardeide, of Leptosoma, and Podargus in their compactness, as well 
as in the definiteness of their areas, as opposed to the more scattered 
and diffused forms they present in Rhinochetus, Eurypyga, Cryp- 
turus, and other birds. But in their exact distribution they differ 
materially from any of these. 
As already described by Mr. E. Bartlett, there are five pairs! of 
powder-patches in Mesites. Of these two pairs are dorsal, two 
ventral, and one lateral in position. All have the form of well- 
defined more or less oval areas, covered by a dense mat of closely 
aggregated long powder-down plumes. 
The most anterior pair is placed close to the median line, the 
patches being only slightly separated from each other, at the com- 
mencement (apparently) of the interscapular region and inclesed 
between the two dorsal tracts, a little before these pass into their 
weaker posterior fork. 
The second dorsal patch is situated on the rump, close to and just 
outside the terminal part of the dorsal tract, between that and the 
posterior termination of the lumbar tracts of each side. 
1 In the Ardeide the number varies from one pair (Baleniceps) to four pairs 
(Cancroma). Three is the most ordinary number. The presence of a single 
cecum in Baleniceps (as fortunately demonstrated by a preparation mounted 
in the Museum of the Royal College of Surgeons), together with these powder- 
down patches, renders its Ardeine nature nearly certain, as already suggested 
by Mr. A. D. Bartlett (P. Z. 8. 1861, p. 131). 
