1921] NATURAL SCIENCES OF PHILADELPHIA, 457 



extreme length of radial trochlea 7.8; greatest length of attach- 

 ment for pronator brevis 6. 



Range. — From Bridger formation, Eocene, near Fort Bridger, 

 Wyoming. 



Remarks. — The broken humerus described above, here exhumed 

 from a resting place among its cold-blooded relatives, the lizards, 

 represents an owl smaller than Bubo virginianus, similar in size to 

 Pulsatrix perspicillata (Latham), that does not resemble closely any 

 existing genus of modern North American owls but in a way combines 

 characters pertaining to several. Minerva saurodosiswas apparently 

 a bird of moderate flight, as processes for muscle attachment, while 

 strong, are not rugged as they are in the Great Horned and Snowy 

 Owls that perform extended migrations. In general outline the 

 humerus of M. saurodosis suggests that of Bubo but with the 

 processes and tubercles developed even to a less degree than in the 

 Barred Owl, Spotted Owl, or Pulsatrix perspicillata. It is judged 

 that it may have been a resident species. 



The generic allocation of this ancient owl is more or less tentative. 

 In 1913, .Dr. R. W. Shufeldti described as Aquila antiqua the hind 

 claw of a bird collected August 4, 1905, by W. J. Sinclair in the 

 Bridger formation at Church Buttes, Wyoming. Later^, Dr. 

 Shufeldt, after study of further material, decided that this species 

 should be relegated to the owls and set up the genus Minerva to 

 receive it. The species, of a size much larger than any exist- 

 ing North American Owls, was characterized bj^ the great pro- 

 longation of the dorsal articular surface of the hind claw. This 

 upper angle projects until the articular facet forms almost half of a 

 circle. This character, while more pronounced in owls than in other 

 groups that I have examined (much more than in available Accip- 

 itriformes) reaches a development in Minerva far beyond that of any 

 modern owl that I have seen. To allow flexibility in movement it 

 must have been received in a deeper pit than ordinary on the distal 

 end of the digital phalanx. Otherwise the hind claw would have had 

 little power of backward flexion. A structure similar to this type 

 of articular facet would be formed by ankylosis of the sesamoid 

 found at the upper end of the claw articulation in many lizards, 

 with the end of the bone. 



1 Bull. Am. Mus. Nat. Hist., Vol. XXXIl, Aug. 4, 1913, p. 297. 



2 Trans. Connecticut Acad. Arts Sci., Vol. 19, Feb., 1915, p. 43. 



