Pterylography of the Tinamiformes. ' 



whilst the hypopteron performs a similar office at the margin 

 of the posterior wing-membrane. 



Apt. alee inferioris (PI. I., Apt.a.inf.). — May be said 

 to embrace nearly the whole of the under-wing surface. In 

 life it is more or less effectually concealed by the posterior 

 row of elongated marginal coverts and the tAvo or three, 

 more or less imperfect and widely separated, rows of t. mi- 

 nores. This space is also somewhat interrupted by the 

 hypopteron (PI, I., Hp.), which joins the double row of 

 feathers previously described (p. 3) as given off by the pt. 

 ventralis (outer branch). 



Vroptjgium (PI. 1., PI. II., U). — Only the elliptical tip 

 of the oil-gland projects beyond the general contour of the 

 body ; this is surmounted by four long, but closely approxi- 

 mated, oil-agglutinated tufts of feathers. 



Filoplumes. — A few long ones occur round the base of 

 the remiges. 



Pulviplumes or powder-down-feathers entirely absent 

 (see p. 17). 



PlumulcB or Down-feathers : — 



Distribution. — Down-feathers are entirely absent on 

 the trunk, but occur on the wing-tract ; here, however, they 

 are strictly confined to the base of the major coverts and 

 remiges. There is a down-feather at the base of each major 

 covert throughout the series, two on the dorsum of every 

 cubital remex, and one in a like position on every primary 

 remex. 



Structure. — The down-feathers possess a long calamus or 

 quill, which breaks up, in the region of the upper umbilicus, 

 into a large number of very long rami. There is no rhachis. 

 The rami bear numerous and moderately long tapering radii, 

 apparently made up of a number of short segments, joined 

 end to end; these segments, proximally, are exceedingly 

 compressed from side to side, so as to be blade-like or strap- 

 shaped ; distally they decrease in width, terminating in a 

 long, fine, free filament. The distal end of every segment 

 appears to be slightly thickened, as if to receive the base of 



