SHUFELDT.] OSTEOLOGY OF THE SPEOTYTO. 601 
the same thing in N. tengmalmi. (P. Z.8., 1871, pp. 739-745.) Figures 
showing this condition are given by Mr. Collett in an interesting paper 
of his that he kindly sent me upon the Craniets og Oreaabningernes 
Bygning hos de nordeuropeiske Arier af Familien Strigide. Mr. Ridg- 
way has likewise figured the skull of Nyctale richardsoni in the North 
American Birds. In Ulula cinerea we have another variety of cra- 
nial asymmetry; in the specimen before me the post-frontal wing is 
thrown farther outward on the right side; this is not the case in Strix 
nebulosa, a species that has a perfectly symmetrical skull. This charac- 
teristic occurs in other Owls. In Surnia funerea we find the osseous 
nasal septum well perforated at its upper and inner part, very much as 
it is in Circus. The Hawk Owl has likewise superorbital processes of 
the same form as those we have described above for Speotyto. The 
periphery of the orbit above in Surnia is slightly rounded, not nearly 
as much though as it is in Strix nebulosa, much less than in Asio. These 
borders are very sharp in Scops, while in Alwco they nearly merge into 
the orbit. This latter Owl has a skull that is at once strikingly differ- 
ent from other forms of the family, being long and narrow, the orbits 
being separated by a great, thick, spongy septum, the wings of the 
ethmoid are likewise spongy cylindrical masses, and the lacrymals are 
very large, being composed of the same material. For a family where 
the skulls of the various forms vary so much, differ so much from each 
other, we note quite an exception in the crania of Nyctea and Bubo, 
owls that have skulls strikingly alike, except in point of size, and a few 
minor differences. 
The spinal column ; cervical portion.—There are fourteen cervical ver- 
tebre, each one having a more or less free movement with the one be- 
yond and-behind it, maintaining in all positions some variation of the 
usual sigmoid curve observable in the division of the vertebral column 
throughout the class. The arrangement, as well as the direction, of the 
planes of the zygapophysial articular surfaces allow considerable rotary 
movement and bending in the vertical plane, with combinations of the 
two. Itis a common habit of this bird, among other of his antics, to 
duck his head smartly downwards and again upwards, several times in 
succession, upon being approached. The relative position of the cervi- 
cals has been figured in Plate I from the dead bird, placed in the act of 
this particular manceuvre, in a specimen after careful dissection. The 
calibre, as well as shape, of the neural canal in this portion of thespinal 
column varies at different points. It originates at the atlas as a trans- 
verse ellipse, with a major axis of four millimetres and a minor axis of 
a little less than three millimetres; this is about the maximum capacity 
throughout the entire canal. From the atlas to the sixth or seventh 
vertebra the ellipse gradually approaches the circle, with a marked 
diminution in size, its diameters being at the seventh about two milli- 
metres in any direction. From this point to the twelfth, inclusive, it 
rises as it fell from the atlas, and in the same manner, when we again 
discover a transverse ellipse, perhaps a jot smaller than the one de- 
scribed in speaking of the atlas. In the thirteenth the canal is smaller 
than, though in all other respects resembles, the twelfth, but an abrupt 
change takes place in shape as we pass to the fourteenth or last cervi- 
cal, where the form of the neural tube suddenly approximates the cir- 
cularity of the dorsal vertebre. The vertebral canal begins, circular, on 
either side at the third cervical vertebra, most of its length being im- 
mediately beneath the prezygapophyses of each segment. It is formed 
in the usual manner by the di- and par-apophysial processes uniting 
laterally with the pleurapophysial elements. Small at the cephalic 
