34 R. W. Shufeldt 



a negative one, i.e., it lacks the osseous tendinal bridge on the lower 

 anterior aspect of the shaft above the condyles. This is the case in all 

 the Owls of this country known to me; but the fact that this bridge is 

 absent in a tibio-tarsus by no means proves that the bone came from 

 the skeleton of an Owl. I have compared this specimen with the 

 tibio-tarsi of all of the large American Owls, including Nydea, Bubo, 

 Strix, etc. The distal extremity of a tibio-tarsus in any of the large 

 strigine forms is very characteristic, and moreover, they are all very 

 much alike. But, as I have remarked, beyond the absence of the 

 osseous tendinal bridge, this specimen possesses none of them. 

 We may compare them thus : 



"Bubo leptosteiis." Bubo virginianus. 



1. Anterior aspect of the shaft, just 1. Anterior aspect of the shaft, just 



above the condjdes, flat. above the condyles, deeply ex- 



2. Inner condyle transversely thick, cavated, with two distinct pitlets 



elongate antero-posteriorly, and at its base. 



reniform in contour. 2. Inner condyle transverselj^ thick, 



3. Outer condyle same form as inner almost circular in contour. 



one, and only half the thickness 3. Outer condyle rather more reniform 

 of it transversely. . in contour, but fully as thick 



4. Mesial surface of inner condj'le transversely as the inner one; 



flush with the border. subcircular. 



5. Intercondj'lar valley of moderate 4. Border prominently raised as a sur- 



width. rounding rim. 



6. (Condyles worn away posteriorly.) 5. Intercondylar valley very narrow. 



7. Shaft above the condyles, posteriorly, 6. Condyles project conspicuously be- 



is flat. hind. 



8. No prominence on side of shaft 7. Shaft above the condyles, poste- 



above the internal condyle. riorly, is concaved. 



8. A marked elevation of the shaft on 

 that locality. 



It is clear from this comparison that the specimen never represented 

 an Owl — ^that is, any typical Owl. 



In my opinion it came from the skeleton of some long extinct 

 generalized form, with strigine afifinities. This is all that can be said 

 for it; and it would be better to await the discovery of more material 

 than to continue to Kst this as a Bubo, when it is so clear that it in no 

 way represents an Owl, and very surely not a Bubo. 



DiATRYMA GIGANTEA Copc. 



{Plate II, Fig. 16; Plate V, Fig. 30.) 



Cope, Proc. Acad. Sci. Phila., 1876, II; also Kept. U. S. Georg. Surv. West of 

 the 100th Merid. (Wheeler's Survey), Vol. IV, Pala;ontology, 70, Plate XXXII, 

 Figs. 23-25. 



