456 



PROCEEDINGS OF THE ACADEMY OF 



[Part III 



(Bridger formation), collected by Dr. James Van A. Carter, between 

 1869 and 1872. 



A bird slightly larger than the Barred Owl, Strix varia Barton; 

 smaller than the Great Horned Owl, Buho virginianus (Gmelin). 



Distal end of humerus much expanded as in other owls, the dia- 

 meter across the condyles nearly twice that of the shaft ; end of ecte- 

 picondylar process broken away, the shaft sloping out to support 

 base of process; lateral epicondyle produced, shelf -like, between 

 base of ectepicondylar process and radial trochlea, confluent in- 

 wardly with base of shaft, with outer margin below ectepicondylar 

 process raised so that the shelf appears excavated (concave), changing 

 outwardly to a shallow groove delimiting the external face of the 

 radial trochlea and disappearing as it comes to the summit of the 

 articular surface; radial trochlea short, roundly elevated, slightly 

 sigmoid in outline, bulging over shelf of lateral epicondyle, sharply 

 declivous on opposite side, at inner end forming a right angle with 

 shaft; ulnar trochlea relatively small, not abruptly elevated above 

 shaft on inner side (articular surface slightly weathered away so 

 that a slight angular tip was formerly present) , slender toward outer 

 margin, so that rounded articular head is reduced; intertrochlear 

 groove narrow, with sharp slope toward radial side 

 and more gradual one opposite toward ulnar 

 trochlea; attachment for pronator brevis exten- 

 sive, roughly elUptical in outUne, relatively more 

 extensive than in modern owls as it is nearly as 

 long as globular portion of ulnar trochlea; attach- 

 ments for pronator longus and flexor carpi ul- 

 naris roughly rounded, well impressed; outer face 

 of median epicondyle expanded on both margins, 

 appearing as a somewhat elliptical expansion at 

 lower end of shaft, slightly impressed on outer 

 face above base of entepicondylar process ; depression 

 for brachiaUs inferior distinct but only slightly impres- 

 sed, more distinct toward ulnar margin; olecranal 

 depression fairly deep, abruptly delimited against 

 median epicondyle, with extent l?ss sharply cut off 

 by expansion of ulnar trochlea, merging impercepti- 

 bly into shaft forward; sulcus anconei lateralis nar- 

 row, shallowly and regularly concave, disappearing 

 after leaving lateral epicondyle; sulcus anconei 

 medius broad, divided into two unequal parts by a 

 slightly raised line passing from upper margin of olecranal fossa ob- 

 liquely to margin of shaft at point where the lateral epicondyle ta- 

 pers gradually into straight shaft; bone hollow. 



Measurements (in millimeters). — Lateral breadth of shaft above 

 depression for brachialis inferior 8.5; breadth across distal end 18.7; 



Fig. 1. 



Minerva sauro- 

 dosis. Anterior 

 view of type. 



Fig. 2. 

 Minerva saufo- 

 dosis. View of 

 condyles. 



