Sin'i-Ki.DT 0)1 tJ/c Osteology of Ciiichis Mcx/ca/zits. 22 1 



Cones, in his Osteology of Colynibns torqitaiiis^ leaves wo doubt 

 in our mind how he regards this projection of the tarso-metatar- 

 sus ; this author says: — "The process of bone representing the 

 OS calcis^ rises at the superior end of the bone, on its posterior 

 aspect, as a very conspicuons crest." 



Professor Morse, in his Tarsus and Carpus of I3irds (Ann. Lye. 

 Nat. Hist., N. Y., Vol. X, 1872), speaks of the centrale, but not 

 in connection with this process. 



In the chick of Ce/itrocercus I found that the rcntrale did not 

 include this process^ consequently in my Osteology of the 7"ei- 

 raonidce (Bull. U. S. Geol. Surv., Vol. VI) I declared that 

 this process had nothing whatever to do with the os calcis, and 

 in the osteology oi Laniiis^ termed it \.he tendinous proces^s. from 

 the fact that the flexor tendons in so many birds either pass 

 over or through it. Now our young of Cinclus mexicamis^ 

 just before it leaves the nest, has its metatarsal bones still ununi- 

 ted, and crowned by a separate segment that has apparently ossi- 

 fied from one single centre, a segment that not only includes the 

 centrale^ but the entire process of which we have been speak- 

 ing. So between Cinclus and Centrocerczts we must still look 

 for other forms to throw light upon this problem. Tlie subject 

 is an extremely engaging one for the ornithologist to look into 

 and investigate. 



The shaft of the tarso-metatarsus of this bird develops after the 

 usual rule set forth in works upon tlie subject, and the same mar 

 be said of the phalanges. 



The writer only hopes that his sketch, necessarih" brief, and 

 far from being exhaustive, will have at least the tendency to in- 

 duce other ornithologists to record their observations upon this 

 subject whenever the opportunity offers. 



Our studies, as far as we have carried them, seem to point 

 pretty conclusively to the fact that our American Dipper is quite 

 closely related to the genus Siz/rus. and not far removed from 

 some of the Wrens. 



