Shufeldt on the Osteology of Cinclus Mexicanus. 2 1 y 
in size to that of their respective owners, and we might, in exten- 
sive series of each, by exceedingly careful measurements, detect 
relative differences. These remarks cannot be applied to the 
genus Harj>drhynchus , as the pelvis there has a very striking 
form, best expressed by saying that it is more angular than the 
others cited, the processes are more pronounced and sharper. In 
Cinclus , as in other forms noted, the bone is broad across, with 
the distal extremities of the pubic bones and ischia flaring well 
outwards ; the ilio-neural canals open ; the sacral vertebrae very 
broad, with numerous foramina or openings existing among them. 
What we have just said in regard to the pelvis applies with 
equal force to the shoulder girdle and sternum ; indeed, this latter 
bone is singularly alike among the various genera that 1 have re- 
ferred to ; the shape it assumes, is that described by Professor Owen 
in his Anatomy of Vertebrates, as the 4 ‘Cantorial sternum,” it 
being the pattern allotted to the vast majority of the class Aves. 
In front we find the manubrium bifurcated, and supported 
upon a stout and produced base, directed upwards and outwards. 
The body behind is 1-notched, the lateral xiphoidal processes 
thus formed having dilated ends. The keel is deep, convex be- 
low, sharp and concave in front, forming an acute carinal angle 
at the point of meeting. The costal processes are very lofty, 
broad and directed forwards, having the facets for the sternal ribs 
♦placed along their posterior borders, which meet on either side the 
xiphoidal borders at a very obtuse angle. The “merry-thought” 
of Cinclus is delicately formed, having expanded upper extremi- 
ties and a median plate below. 
Our subject has, in addition to the usual number of bones, in 
the pectoral limb, quite a sizable sesamoid, to be found at the 
back of the elbow ; this bonelet is likewise found in Oreoscoptes 
and may be a common character of other birds we have men- 
tioned. The arm seems to be completely non-pneumatic, indeed 
I have failed tg find the apertures for the entrance of air in any 
of the bones composing it. Several months ago my attention 
was directed to a note, I think in the Proceedings of the Zoologi- 
cal Society of London, in which some English observer says the 
same of the European Dipper. This, non-pneumatic condition 
of the long bones, not only of the upper but also of the lower ex- 
tremities, seems to hold good among all the other forms and 
genera we have thus far referred to in this article. 
