1900.] SHUFELDT—OSTEOLOGY OF THE STRIGES. (Ges 
in the Journal of Morphology (Boston, U.S. A., Vol. XVII, No. 1, 
1900, pp. 119-176, Figs. 1-7, Pls. XV-XX). Taken in connection 
with all we have already recorded upon the skull of these birds in 
several genera, it will not be necessary to dwell upon this part of 
the skeleton in Syrnium, as the figures to which allusion has just 
been made will be fully sufficient to show the special characters and 
form of it. (See Pl. XIII, Figs. 13 and 15.) One point of note is 
to be observed, however, and that is in some species of Syrnium 
the skull is symmetrical, while in some others asymmetrical distor- 
tion to a moderate degree is observable. Of the first condition |S. 
nebulosum is an example, and of the latter S. cimereum furnishes us 
an instance. It is symmetrical in Pulsatrix torquatus. (Pl. XVIII, 
Fig. 13.) In this genus Syrvzum the outer pair of notches of the 
sternum are conspicuously deep ; the manubrium is well pronounced ; 
the coracoidal grooves slightly cross each other; the clavicles are 
firmly united below, and the os prominens is of some considerable 
size. An interesting little point is seen in the femur, where the pit 
in the head of the bone for the ligamentum teres is very much deeper 
than is usually the case among birds. 
Another Owl that exhibits a peculiar asymmetry cf the cranium is 
Scotiapex c. lapponica; here the postfrontal wing is thrown farther 
outward on the right side, something after the order found ina 
species of the genus Syrazum, to which we referred in the last para- 
graph.’ 
Probably the best examples of cranial asymmetry among the 
Strigide are to be seen among the representatives of the genus 
NVyctala, as, for instance, in JV. fengmalmt. Tere it does not in- 
volve so much the position of the postfrontal processes as it does 
distort the squamosal region of the skull upon either side. A skull 
of this bird has been nicely drawn for us by Collett, as stated above, 
and republished by me in the translation of his paper. 
How such a condition as this asymmetry came to be evolved will 
probably remain one of those enigmas in zodlogy not to be solved 
through the researches of man. It is difficult for me to see what 
1 This statement in reference to Scotiafex must, for the present, be taken with 
caution, as the observation was made by me upon a skeleton so labeled in the 
United States Army Medical Museum at Washington, and I know to my cost 
that the diagnoses of specimens in many cases in that collection are incorrect to a 
degree probably unparalleled in any institution in existence. In my own collec- 
tion I have but the trunk skeleton of Scotiapex. 
PROC, AMER. PHILOS. SOC. XXXIx. 164. UU. PRINTED JAN. 19, 1901. 
