A FLIGHTLESS AUK, IVI ANCALLA CALIFORNIENSIS, FROM 
THE MIOCENE OF CALIFORNIA. 
By Frederic A. Lucas, 
Acting Ciirdior of Yertehrale Fossils 
The name Jfajiealla caHforniensis is proposed for a fossil llightless 
auk, i-eprosented l)}- a nearly complete left humerus found in excavat- 
ing Third street tunnel at Los Angeles, California, in strata considered 
by Mr. W. H. Dall as belonging- to the Upper Miocene or Lower Plio- 
cene, probably the former. The type is No. JrOTG in the catalogue of 
fossil vertebrates, U. S. National Museum. The genus is character- 
ized by a short flattened humerus, devoid of the customary sigmoid 
flexure, l)y the moving of the articular head of the humerus toward 
the ulnar border, and l)y the development of the ridge for the attach- 
ment of the brachialis inferior muscle. Total length of specimen 
68 mm. 
That the bird was flightless is shown at once by the shortness and 
flatness of the humerus, and further by the fact that the bone lacks the 
slightly sigmoid shape characteristic of the humeri of flying birds, 
being instead slightly concave on the ulnar border. Absence of the 
power of flight is also shown by the moving of the articular head of 
the humerus toward the ulnar side, as in birds which fly well the 
articular face is well toward the radial border. In the penguins this 
face is as far dow^n on the ulnar border as the lowest point of the 
inferior crest, and in the flightless Great Auk the articular surface is 
nearer the ulnar border than in any other member of the auk family 
save the one under consideration. The inferior crest is stout and well 
developed, and incloses a large subtrochanteric fossa. This is pierced 
for an artery, and so is the corresponding fossa of the Great Auk, while 
no such perforation is present in the specimens of Lomvia, Alca, or 
L}inda examined. 
The humerus has a larger medullary cavity than has the correspond- 
ing bone of the Great Auk, and it is interesting to recall that the leg 
bones of Hesperonis, the most highly specialized of aquatic birds, 
Proceedings U. S. National Museum, Vol. XXIV— No. 1245. 
133 
