Vol. 5] Miller.— Wading Birds of Ranch o La Brea. 



447 



Distal trochlear region much less flattened. This character 

 is most clearly shown by a comparison of dimensions given in the 

 table below. The ratio of the greatest transverse diameters in 

 the two species is 100:62, while the ratio of the 

 greatest sagittal diameters is 100 :83 ; or again, 

 the ratio of sagittal to transverse diameters is 

 100:95 in G. minor as against 100:74 in G. cana- 

 de nsis. 



The entocondyle as seen from the front is 

 proportionately smaller. Its ratio to the ecto- 

 condyle is 100 :65 in G. minor, as against 100 :80 

 in G. canadensis. 



Other differences not easily measured are 

 noticeable in the intercondylar tubercle, which is 

 less produced and has its summit less knob- 

 shaped. The supratendinal bridge is narrower 

 and is not crossed obliquely from within by a 

 distinct ridge. The region of attachment of the 

 outer end of the tendinous bridge is less flattened. 



The generic characters of Orus are well dis- 

 played in the inequal condyles and the wide in- 

 tercondylar gorge marked near the middle by a 

 secondary transverse depression ; the depressed 

 osseous bridge with its prominent tubercle ; the 

 deep extensor groove, rounded where it plunges 

 under the osseous bridge, but flattened to a sharp- 

 lipped slit where it emerges again distally. 



In the type specimen the crests and ridges Fig. 8. 



are sharply defined and the texture of the bone ' em \ f ' tibio- 



is such as to leave no doubt but that it is part tarsus from an- 

 terior side, nat- 



of an adult individual. nral size. 



Table of Measurements. 



Tibia, no. 12533. 



Greatest transverse diameter through condyles 18.8 mm. 



Greatest sagittal diameter through condyles 17.9 



Depth of anterior aspect of ectocondyle 12.3 



Depth of anterior aspect of entocondyle 8.3 



Least transverse diameter of shaft 10.2 



Least sagittal diameter of shaft 8.3 



Width of osseous bridge 5.9 



