1916] 



Miller: Owl Remains from Bancho La Brca 



103 



Tibiotarsus. — This segment of the limb shows a partial reversal of 

 characters of the two species as displayed by the tarsometatarsus — a 

 reversal which is liable to produce confusion. Corresponding bones 

 from the same individual discussed above show A. wilsonianus to have 

 the advantage in length, although the difference is less in proportion 

 than in ease of the shank. The greater robustness of wilsonianus is 

 apparent and marked. Confusion might however arise between a 

 female of flammeus and a male of wilsonianus. Such a possibility is 

 illustrated by a tibiotarsus from the same section of the excavation 

 with other remains of both species of Asio. It is shorter and yet more 

 slender than the' nnsexed specimen of flammeus, so the question of its 

 identity is a difficulty one to decide. Study of a series of Asio material 

 from the asphalt, together with the two Recent specimens, points to 

 the conclusion that the Recent specimen of A. flammeus is a female 

 and that the Recent specimen of A. tvilsonianus is a fully adult bird, 

 though not the maximum in tibial length. A single fossil specimen 

 appears slightly longer and less robust by an almost imperceptible 

 degree. 



Humerus. — In sharp distinction to the posterior limb, the humerus 

 of Asio flammeus has the short, stout, proportions of a larger bird of 

 strong flight. The bones of the Recent specimens are almost identical 

 in length but the greater robustness in flammeus is recognizable at a 

 glance. The transverse and the sagittal diameters at all points give 

 the humerus of A. flammeus an appearance of much greater strength 

 of flight than is possessed by the associated A. tvilsonianus — a con- 

 clusion quite in harmony with the fact that the former species occurs 

 unmodified over a large part of the globe and has been taken by deep- 

 water ships as much as eight hundred miles at sea. 



ASIO WILSONIANUS (Lesson) 

 Found fairly commonly in the asphalt, represented by most of parts 

 of the skeleton. 



ASIO FLAMMEUS (Pontoppidan) 

 Found associated with the last-named species and in about equal 

 numbers. 



