2 1 8 Shueeldt on the Osteology of Clnclus Afexicamis. 
The proximal extremity of the hwnerus is very much expand- 
ed, and rather abruptly bent in the direction of the bird’s body, 
the member being considered in a position of rest. The “crest” 
we know curls over the usual site of the pneumatic fossa, which 
depression is divided by a bony partition from a lesser cavitv 
above. This characteristic is also more or less strongly marked 
in the Rock Wren, Siurus , and others, and is feebly shown in 
Ha rp o rhyn chus. 
The articular cavity of the shoulder joint is increased in the 
Dipper by a good sized os humero-scapalare , a sesamoid that we 
are aware is to be found among other orders. 
We will present the reader here with a table showing the rela- 
tive lengths, etc., of some of the bones we have thus far examined, 
in order that a study of their comparative development may be 
made. (The measurements are given in centimeters.) 
Sternum. 
Species. 
Length 
from bifur- 
cation of 
manubrium 
to end of 
body. 
Depth of 
keel. 
Humerus. 
Radius and 
ulna. 
Hand. 
Long axis 
of skull. 
Cinclus 
mexicanus. 
2.7 
0.8 
2.2 
2.6 
2.6 
4.4 
Siurus 
ncevius. 
1.9 
0.6 
i -7 
2.1 
r -7 
3 -i 
Salpinctes 
obsoletus. 
1.6 
0.5 
i -7 
2.0 
i -7 
3-6 
Oreoscoptes 
montanus. 
2-3 
0.7 
2.2 
2.7 
2.4 
4.2 
Si alia 
mexicana. 
2.3 
0.8 
2.0 
2.8 
2-3 
3-5 
Antkus 
ludovicianus 
2 . 1 
0.7 
r.8 
2.5 
2.1 
2.9 
Merula 
migratoria. 
3-4 
1. 1 
2.9 
3-4 
— 
— 
Hesp>erocich- 
la ncevia. 
3 '° 
1.6 
2-5 
3 *i 
3 -i 
4.6 
A great many points of extreme interest and of the highest im- 
portance reward the ornithotomist’s study of the pelvic limb of 
Cinclus ; some of these the writer has already remarked upon 
in papers now in press, but he offers them here again, confident 
of the fact that they will be of interest to ornithologists generally, 
