28 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 85 



broad and flattened both in front and behind, the anterior margm 

 of the inner condyle produced over the shaft in a slight overhang; 

 no supratendinal bridge. Bone strongly fossilized, dull brownish 

 gray in color, somewhat distorted by crushing. 



Measurements. — Transverse breadth across condyles, 11.5 mm; 

 transverse breadth of lower end of shaft, 8.9 mm. 



Remarks. — Though in somewhat worn and distorted condition the 

 fragment described above shows so definitely the characters assigned 

 at present to the family Protostrigidae that it was identified as of 

 that group at once on casual preliminary examination. 



In general form Protostrix mimica is closely similar to P. lep- 

 tosteus as indicated in the diagnosis, smaller size being its main 

 characteristic. The size difference between the types of these two 

 species has been carefully checked with differences existing between 



Figure 4. — Protostrix mimica, new species: Distal end of tibiotarsus (type). Natural 



size. 



male and female in species of modern owls to find that the amount 

 is more than covered by this sexual variation. In addition, the 

 outer condyle is somewhat thicker. Possibly the two belong in 

 separate genera, but with so small a representation of both of the 

 species concerned it is considered best to list them as congeneric. 



As Protostrix saurodosis (Wetmore) is intermediate in size between 

 the barred and great horned owls, P. mimica is decidedly smaller. 



In the same locality and horizon Mr. Walker secured the distal 

 end of a right tarsometatarsus (fig. 5) that I consider also to repre- 

 sent the species here described. The specimen (U.S.N.M. no. 14874) 

 is slightly distorted by pressure and has part of the slender processes 

 of the lateral trochlea missing, but it is sufficiently complete to indi- 

 cate its characters. I have no hesitancy in identifying it as coming 

 from a member of the Protostrigidae, and its dimensions are such 

 as to indicate that it comes from a bird the size of P. mimica. It is 

 logical therefore to place it with the species of that family from 

 the same collecting locality. 



Following is the detailed description of this fragment: Outer 

 trochlea in lateral outline comparatively broad and rounded, pro- 



