* 
21 6 Shufeldt on the Osteology of Cinclus Mexicanus. 
and D in the cuts, this feature in the opposed forms mentioned 
above occupying a position between the superior orbital margins. 
There is still another very marked distinction among the birds 
we have thus far compared, and that is in the general external 
form of the brain-case proper. A and B show the form assumed 
by the genera we mentioned above in connection with them ; 
smooth, large, and globular, all indicating the possession of a 
brain of no mean size as compared with the owner. In Cinclus , 
Slums , and the Troglodytince the prominence of the supra- 
occipital eminence causes depressions to exist at d and d ’ that 
are not present in A and B at c and c'. 
With regard to this last characteristic the outline assumed by 
Siurus seems to claim the nearer place, over the other forms 
mentioned. 
So much for the skull, and the writer must reluctantly and 
with as good grace as possible allow the student to observe other 
interesting points of difference for himself, though he would be 
only too glad to assist him in this part of the 'skeleton. 
There are fourteen cervical vertebras in Cinclus , the last two bear- 
ing each a pair of free ribs, the ultimate pair possessing uncinate 
processes ; this arrangement holds good in Siurus and Salpinc- 
tes , but we remember that in Eremophila* we found only thirteen 
cervical vertebras ; the number of ribs varied however. Cinclus also 
possesses, in common with the form mentioned, four dorsal ribs ; 
these are connected with the sternum by sternal ribs, the first sa- 
cral vertebra possessing an additional pair, but its sternal ribs only 
articulate along the hind border, on either side of the true sternal 
and last pair. This condition obtains, we know, in very many 
birds 
If we do not include the pygostyle or last coccygeal vertebrae, 
we observe that Cinclus has seven caudal vertebrae, Siurus and 
Salpinctes each only five , Oreoscoptes having six, so that the 
number of these segments may vary more or less among the 
genera we have quoted above. 
The general pattern of the pelvis of the Dipper, the Wrens, 
the Thrushes, and Sicilia is pretty much the same for all, that is 
it would be very hard to point out decided differences among 
them upo'n casual examinations ; of course they are proportionate 
* See Bull. U. S. Geol. Surv., Vol. V, Art. 5. 
