304 MR. AV. p. PYCRAFT ON THE [^P''"- 1^, 



we meet with a type of pelvis found elsewhere only amongst 

 the Stiiges. Its chief characteristic is the great deflection and 

 shortening which the postacetabular ilium has undergone, and 

 this is moie marked in the Accipitiine innominate. The 

 innominate bone of the Owls can, however, it would seem, be 

 readily distinguished by the fact that the ischium is invariably 

 produced backwards into a more or less slender spine resting 

 on the pubis. 



In its general confoi-mation the pelvic gii-dle of the Falconi- 

 formes, after the elimination of the Gypogeranidpe and Cathartse, is 

 very uniform : modifications fi-om the type are very considerable. 

 Some of the more noticeable, however, may profitably be com- 

 mented upon hei'e. The most conspicuous depai'tvii-e from the 

 type is found J. in the pelvis of Pandion (text-fig. 37, p. 305), 

 which is remai-kably broad. This great breadth is due partly to the 

 length of the outstanding ti-ansverse processes of the synsaci'um, 

 which suppoi't the roof of the anterioi- and posterior renal fossse ; 

 and jjartly to the exceptionally broad doi-sal plane of the post- 

 acetabular ilium. The pieacetabular ilium is sharply truncated 

 anteriorly, and is widely sepaiated from its fellow of the opposite 

 side : so much so that a tubular aperture — the cancdis ileo- 

 lumhalis — is left at the point where the mesial curved border 

 leaves the synsaci'um. The glenoid surface of the antitrochanter 

 is oblong in shape and curved backwards. The iiio-ischiadic 

 foramen is of great size. The obturator foramen is also very 

 large, and closed posteriorly by the approximation of the pubis 

 to the infeiior border of the ischium, which, we may remark, 

 turns abi'uptly upwai'ds at its hinder end. The pubis is long, 

 and develops a crescentic plate the cephalad segment of which 

 fits closely to the upturned ischial bordei- ; beyond this it is con- 

 tinued backwards for a considerable distance as a rod-shaped bar 

 nearly meeting its fellow of the opposite side. 



The pelvis of Pandion (text-fig. 37, p. 305) is an exaggeration 

 of the typical Accip-itiine pelvic girdle, which maybe very well re- 

 presented by such a foiin as is presented in Polyhorus for example. 

 Herein the pre- and postacetabular ilia are about equal in length. 

 The former is a moderately broad concavo-convex plate directed 

 outwards and downwaids, meeting its fellow of the opposite side 

 in the middle line, and having its superior border accentuated by 

 a sharply-defined outstanding crest, which, in some forms, as in 

 Haliaetus and Parabuteb for example, becomes still more sti-ongly 

 accentuated, forming an almost shelf-like pi-ojection. This border 

 is continued backwards to terminate in an overhanging supra- 

 trochanteric process. The postacetabular ilium expands into 

 broad doi'sal plates, terminating somewhat abruptly some distance 

 from the end of the ischium, with which it is fused. InAccipiter 

 and Elanus, and still more markedly in Polyboroides, the dorsal 

 border of the ischium turns sharply inwards so that the dorsal 

 plate of the ilium forms a relatively enormous ledge overhanging 

 a deep cavern passing forwards into the obturator foiamen. In 



