2l6 Shufeldt 0)1 tJic Osteologv of Citiclits J\lexican?ts. 



and D in the cuts, this feature in tlie opposed forms mentioned 

 above occupying a position between the superior orbital margins. 



There is still another yery marked distinction among the birds 

 we have thus for 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^ 

 Shir7ts^ and the Troglodytliice 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 

 Shirus 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 vertebrje in Cinclus^ the last two bear- 

 ing each a pair of free ribs, the ultimate pair possessing uncinate 

 processes ; this arrangement holds good in Siiirus and Salpinc- 

 tes^ but we remember that in Eremophila* \\q found only thirteen 

 cervical vertebra ; the number of ribs varied however. Cinchis 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. Tliis condition obtains, we know, in very many 

 birds 



If we do not include the pygostyle or last coccygeal vertebra\ 

 we observe that Cinclns has seven caudal vertebrae, Siitriis and 

 Salphictes each only five^ Oreoscoftcs having slx^ 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 Sialia is pretty much the same for all, that is 

 it would be very hard to point out decided differences among 

 them upon casual examinations ; of course they are proportionate 



* See Bull. V. S. Geol. Surv., Vol. V, Art. 5. 



