900.] SHUFELDT—OSTEOLOGY OF THE STRIGES. Tas 
tarsus, as well as an ascending process of the astragulus. The latter 
is quite conspicuously marked. Fibula is noted for its length, but all 
signs of a fibular articular ridge on the side of the shaft of tibio-tarsus 
are still wanting. The two bones simply lie alongside of each other, 
faint indications of any coéssification being seen only at their distal 
ends. Fusion is fairly well advanced among the metatarsal elements, 
omitting, as I do of course, the small accessory one for hallux, which, 
as we know, remains permanently free throughout life. Finally, the 
bones of the feet are seen to be in a stage of ossificatory advance well 
in keeping with the other elements of the limb of which I have just 
been speaking. 
Other Owls of the United States avifauna present us with very 
interesting characters in their osseous systems. Upon examining a 
skeleton of Asto wilsonianus (Pl. XV, Figs. 22 and 23; also Pl. XVII, 
Fig. 30), we are confronted in it with a strigine skull quite different 
in its pattern from anything we find in Buvdo. In conformation it 
is symmetrical, so far as its auricular region is concerned. Both 
nasal and interorbital septa are absolutely entire, and I have yet to 
see a skull of this species that has a perforation in either of these 
partitions. One of the most characteristic features is the manner in 
which the postero-superior margin of either orbit is broadly flattened 
out, while each supraorbital process is decurved, pointed and prom- 
inent, and projects over the middle point of the orbit from above, 
The tympanic bullz are large and open; the postfrontal processes 
rather small and jutting well out from their bases. Behind these, 
on either side, another long spiculiform process is sent down in front 
of the quadrate. It is directed forward and downward. The pars 
plana is upon the bubonine type, and the maxillo-palatines are of 
fairly large size. Coming to the vomer we find it of some consid- 
erable size, being pointed in front and fused with the palatines 
posteriorly. Both the pterygoids and the quadrato-jugal bars are 
straight and unusually slender for an Owl. The pterygoidal heads 
of the palatine bones are conspicuously separated, a condition that 
throws the anterior ends of the pterygoids themselves widely apart 
in this skull. They are never in contact, I believe, in any Owl. 
Asto is noted for another feature in its skull—this is the peculiar 
flatness of the posterior aspect of the cranium, as well as its unusual 
width and height for a skull of its comparative size. 
Finally, we are to note that the interorbital septum is relatively 
much thicker in the transverse direction than we find it in other 
