MORPHOLOGY OF THE OWLS. 35 



Further, the tarso-metatarsus of the Striges, as a whole, may be readily distinguished 

 from that of Pandion, iuasmvich as in the former the hypotarsus is simple, in the latter 

 compound. 



The metacarpal I is relatively smaller than in the Falconiformes. 



The phalanges of the Striges differ from those of the Buteonine section of Accipitres 

 among the Falconiformes only in the matter of tlieir respective lengths in different digits. 



Ph. 1 D. II is very short, being only about half as long as Ph. 2 ; Ph. 1 of D. Ill is 

 also very short, so also is Ph. 2, though slightly longer than Ph. 1; Ph. 3 is long, about 

 as long as Ph. 1-2 combined ; Ph. 1, 2, 3 of D. IV are all extremely abbreviated, their 

 combined length being less than that of Ph. 4. The ungual phalanges are all very large, 

 and in the larger species have the base encircled by a broad raised collar. 



Tlie phalanges of the Strigidse differ from those of the Bubonidse in that Ph. 1, D. II 

 is long, so also is Ph. 2 of D. III. 



X. Observations on Generic and Specific Characters. 



I hoped, when I commenced the present section of the memoir, to be able to give 

 diagnostic characters, not only for every genus, but also for the bulk of the species in 

 each genus. Unfortunately, this Collection, though undoubtedly an exceptionally good 

 one as compared with that of other Museums, is still far from complete — so much so, 

 as to render it impossible to fulfil my anticipation. 



Many genera are entirely wanting, and those we have are represented for the most 

 part only very imperfectly. Thus the genus Syrnlmn is represented, according to 

 Dr. Sharpe, in his ' Hand-list of Birds ' (26), by 31 species. The Museum Collection 

 contains but 3. Ciccaha, with 8 species, is represented only by 1. Ninox, with 14 species, 

 by 2. Scolds, with 80 species, by 3. 



It is extremely unlikely that all the species in such large genera will prove specifically 

 distinct, according to the skeletal characters; but I think it certain that a very 

 considerable number will be found to be more or less easily distinguishable if the sum 

 total of all the osteological characters be taken into account. At least three examples of 

 each species of a genus are necessary before full reliance can be placed on the apparent 

 specific characters, but the following analysis is intended to show what may be done. 



The genus Asio is represented, according to the ' Hand-list of Birds,' by 14 species ; of 

 these, five are possessed by the Museum — A. otus, A. accqntrliim, A. madagascariemis, 

 A. nisueUa, A. major. 



The skulls of A. acclp'driims and madaguscarlensis are readily picked out from the 

 skulls of A. otus, nisuella, or major, by reason of the fact that the postorbital process on 

 its outer border bears a prominent projecting tubercle for the attachment of the mem- 

 branous valve dividing the cavernum from the diverticulum in the external asymmetrical 

 ear. This tubercle is represented by a mere vestige in the remaining species. Further, 

 the latter are characterized by the greater prominence of their supraorbital processes, 

 and greater width of the " post-cavernum " — the uppermost limit of the tympanic cavity. 



A. accipitrinus and A. madagascarietms are also distinguishable by their skeletons: 



5* 



