—_— Mer 
CONDITIONS OF THE PODOTHECA. 47 
§ 80. Wnuen the harder sorts of either scutella or plates are roughened 
without obvious elevation, the leg is said to be scabrous or scarious. But 
scabrous is also said of the under surfaces of the toes, when these develop 
special pads, or wart-like bulbs (called tylar?) ; excellently shown in most 
hawks. The softer sorts of legs, and especially the webs of swimming 
birds, are often crosswise or otherwise marked by lines, without these being 
strong enough to produce plates; this is a condition analogous to the little 
raised lines and depressions seen on our own palms, and especially our 
finger-tips. _ Occasionally, the plates of a part of the lez become so devel- 
oped as to form actual serration; seen on the hinder edge of the tarsus of 
grebes. 
ii 
\))) 
MN 
4 
Fig. 9. “Booted” tarsus, of a robin. Fiec.10. Scutellate tarsus, Fie. 11. 6b. Seutellate tarsus, of a 
of a cat-bird. pigeon; a. reticulate tarsus, of a 
plover. 
§ 81. Wuen an unfeathered tarsus shows on its front surface no divisions 
of the podotheca, or only two or three divisions close by the toes, it is said 
to be booted, and the podotheca is said to be fused. (Fig. 9.) This con- 
dition chiefly occurs in higher Oscines, and is supposed by many, particu- 
larly German ornithologists, to indicate the highest type of structure; but 
it is also found in some water birds, as Wilson’s stormy petrel. It is not a 
very common modification. Among North American birds it only occurs 
in the following cases:—Genera Turdus (1), Cinclus (5), Sawicola (6), 
Sialia (7), Regulus (9), Chamea? (11), Myiadestes (52) and Oceanites 
(307) ; and even these birds, when young, show scutella, which disappear 
with age, by progressive fusion of the acrotarsial podotheca. 
§ 82. Tur Crus, when bare below, may present scutellation either before 
or behind, or both, as is seen in many waders where the crus is largely 
naked; often again, the crural podotheca may consist of loose, softish, 
movable skin, not obviously subdivided: sometimes it is truly reticulate, 
as in the genus Heteroscelus (221). 
§ 83. Tur Tarsus, in general, may be called subcylindrical ; it is often 
quite circular in transverse section ; very rarely thicker across than fore-and- 
aft (as in penguins); but very often thicker in the reverse direction. 
When this transverse thinness becomes noticeable, the tarsus is said to be 
