518 MB. K. LTDEKKER ON SOME [June 6, 



of imperfect) bones is frequentlj' a matter of extreme difficulty, if 

 not of actual impossibility. 



Steix sa>-cti-albani, n. sp. (Plate XLI. figs. 1-4.) 



In the British Museum Catalogue of Fossil Birds I took the 

 family Strigidce to include all the members of the nocturnal birds 

 of prey, but I have since seen reason to adopt the subdivision of 

 the o'l-oup into the families Strigidce and Buhonidce. And I am 

 the more confirmed in this latter view from the circumstance that 

 the specimens under consideration show an osteological distinction 

 between the members of those two families which I have not 

 observed recorded in the works with which I am familiar. 



Of all the birds represented in the collection the one of which 

 the remains are most numerous is a species of Owl belonging to 

 the oenus Struv — no less than eleven more or less imperfect 

 bones beiug referable to this form. From these specimens I have 

 selected four for illustration (see Plate XLI.) — those represented 

 in fio-ures 1 and 2 being the distal portions of the right tibia, 

 while those in figures 3 and 4 are respectively the proximal and 

 distal halves of the left tarso-metatarsus. The Strigine affinities 

 of these specimens are amply demonstrated by the form of the 

 lower end of the tibia, in which the condyles are remarkably 

 prominent, while there is no bridge over the extensor groove on 

 the anterior aspect; and likewise by the highly convex arch 

 formed by the distal trochleas of the tarso-metatarsus, and the 

 general form and prominence of the crest on the hinder part of 

 the hypotarsus. Although I am not aware that any sharply 

 defined distinction can be drawn between the tibia of the Bubonidfe 

 and Strigidce, I find that Strix differs from all the members of the 

 former that I have been able to examine in the absence of the 

 bony bridge over the extensor depression of the upper part of the 

 anterior face of the tarso-metatarsus. As this bridge is wanting 

 in the specimens before us (fig. 3), and as they agree other^A^se in 

 general form and size with the corresponding bones of the Barn- 

 Owl, I opine that they must be referred to the genus Strix. 

 Agreeing in size with the corresponding elements in S.flammea, 

 they are distinguished by the grooves between the distal condyles 

 of the tibia being somewhat less deep ; while the tarso-metatarsus 

 has a deeper posterior groove and a smaller crest to the hypotarsus. 

 The only fossil representative of the genus which, so far as I am 

 aware, lias received a distinct name is <S'. meliten^is\ founded on a 

 femiu" from the Pleistocene of Malta, which differs from that of 

 S.flammea in its more slender proportions. As there are no 

 indications of a similar slenderness in the bones under considera- 

 tion, I think I shall be justified in assigrdug them to a new species, 

 under the name of S. sancti-albani. The specimens do not, 

 however, admit of defining the species more exactly than by the 

 above-mentioned features in which it differs from S. flammea. 



' Lydekker, Cat. Foss. Birds Brit. Mus. p. 13 (1891). 



