158 MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 
than those included in the general remarks on the arrangement of the coverts. There 
are only two median coverts in the hand, and, as already hinted, one of these may 
represent the carpal remex. 
T. minores.—There are 6 to 7 rows of minor coverts on the cubitus. They are 
wanting in the manus. 
T. marginales—A broad bare space separates these from the minor coverts. They 
are arranged along the pre-axial border of the wing, in groups of 3, just as in some - 
Neognathe. They are wanting in the hand. 
Ala spuria.—There are 5 thumb-quills, as in the Meognathe. 
Parapteron and Hypopteron.—These humeral remiges are wanting in Rhea. 
The feathers along the pre-axial border of the humerus are of great length. 
The whole under surface of the wing is perfectly bare, a probably degenerate 
character. 
Pt. caude.—There are no rectrices. 
Uropygium.—Absent in adult (p. 159.) 
The Rhamphotheca, like that of Dromeus, is made up of three pieces, both in the 
sheath of the upper and lower jaws. ‘There is no trace of the denticulations found in 
Dromeus, either in the adult, nestling, or embryo. The aperture of the nostrils, 
which are pierced through the cere, is lateral. 
The Podotheca of Rhea americana (fig. 1 D), according to Dr. Gadow [25], resembles 
that of R. darwini, and differs from that of R. macrorhyncha in that the whole of the 
acrotarsium is clothed in large scutes, whilst in R. macrorhyncha these scutes are 
confined to the distal extremity. The leg of this last thus resembles that of Caswarius 
and Dromeus. R. darwinii is furthermore peculiar in that the feathering of the 
tibio-tarsus is continued downwards on to the tarso-metatarsus for some distance. 
It is interesting and significant to note, however, that a few feathers occur in this 
region in the embryo of &. americana. Indeed, in this latter their extension may be 
traced downwards to within a short distance of the toes, as will be seen in fig. 2, p. 155. 
The planta is also invested by large scutes. In the 3-grown nestling and adult 
these are arranged in the form of a series of paired plates. In the nestling and ripe 
embryo they form a series of single transverse scutes. Along the inner side of these 
large scutes will be found a number of smaller, wedged in between the larger. These 
apparently gradually increase in size, and thus give rise to the secondary arrangement 
of paired plates. 
The claws of the toes are laterally compressed, and form a strong median dorsal 
ridge or keel, not met with in other Palwognathe. This is most marked in the 
outer and inner toes. 
