32 ME. W. P. PYCEAPT ON THE 



The humerus of the Strigidae diflFers from that of the Asionidse mainly in its greater 

 slenderness, and in the feeble development of the various crests and tuberosities. 



The humerus, in the adult, is larger than the manus, but shorter than the forearm. 

 The humerus of the Striges may be distinguished from that of the Caprimulgi by reason 

 of the extremely well-defined radial tuberosity and the deep incisitra capitis seen in the 

 latter. In the Owls these are not conspicuously developed. 



The forearm offers no characters of systematic importance. 



The ulna has a well-developed olecranon process, feebly developed tubercles for the 

 remiges and under tail-coverts, and affords a large articular surface for the radius. Two 

 distinct glenoid surfaces are developed on the palmar surface for the articulation of the 

 metacarpus. 



The radius, which is much more slender than the ulna, is more or less sigmoidally 

 curved, the distal half running j)arallel with the ulna, leaAdng but a narrow space between. 

 The forwardly bowed portion of the shaft starts abruptly from the proximal moiety 

 involved in the articulation with the humerus, giving the cotylus for the radial tuberosity 

 of the humerus the apj^earance of being supported on a rather long neck. A large 

 sesamoid, the os 2)rominens, is generally found attached to the distal end of the radius, 

 as in some Falconiformes, e. g. Elanus among the Accipitres. In Ninox connivens this 

 OS prominens is of relatively enormous size, and should be carefully examined in the 

 living bird. 



In a considerable number of Owls the second fifth of the radius develojis from its post- 

 axial surface a delicate arch of bone for the extensor metacarpi radialis hrevis. Is this 

 character to be regarded as due to kinetogenesis ? 



The carpal bones call for no special comment : the most interesting character which 

 they present is a deep indentation on the radiale for the reception of the tubercular meta- 

 carpal I when the wing is fully extended. 



The manus is long and slender. The carpo-metacarpus may be distinguished from that 

 of the Accipitres by the fact that the Mc. Ill joins the shaft of Mc. II distad of the 

 Mc. I. The trochlea for the ulnare lies on a level with the inferior border of Mc. Ill, 

 and not in the middle line of this as in the Falconiformes. The intermetacarpal space 

 is wide. 



Phalanx 1 of Mc. II has a deeply emarginate postaxial border, the proximal end being 

 cut away so as to leave a cylindrical shaft, whilst the distal end is expanded to form a 

 broad plate for the support of the remiges. Ph. 1 of D. Ill presents a deeply emarginate 

 postaxial border, the proximal end being broad, the distal end tapering. 



The proportions of the various segments of the wing appear to vary considerably 

 between the nestling and adult stages. The measurements afforded by a comparison of 

 two nestlings of Speotyto, of different ages, and an adult illustrate this. 



In the youngest nestling in the Museum Collection (98.5.7.39) the humerus is 

 slightly longer than the forearm, whilst the latter and the manus are almost subequal. 

 In a second specimen (98.5.7.38) the humerus is conspicuously shorter than the fore- 

 arm, whilst the latter is now markedly longer than the manus. In the adult, the humerus 

 is one-quarter shorter than the forearm, and the disproportion between the latter and 



