1902.] 



OSTEOLOGY OF THE FALCONIFORMES. 



319 



C. Coi'piis sterni with posterior border notched, fenestrated, or entire; coracoid 

 grooves overlapping ; acrocoracoid with well-marked facet for articulation of 

 furcula ACCIPITRES. 



Key to Families of the Accipitres. 



A. Spina externa and interna well developed; procoracoid large, articulating with 



clavicle Faxconid^. 



B. Spina externa only present ; procoracoid articulating with scapula only and 



widely separated from clavicle Accipitbidj3. 



0. Pelvic Girdle. 



Preacetahular ilium very long and with the external lateral border more or less 

 markedly concave ; pectineal process wanting ; supra-trochanteric processes generally 

 prominent and raised high above anti-trochanter ; pubis, when present, generally 

 closely approximated to the ventral border of the ischium. 



A. Postacetabular ilium shorter than ischium, but without a notch indicating the 



two elements posteriorly SERPENTARII. 



B. Postacetabular ilium shorter than ischium, and the limitations of the two 



elements indicated posteriorly by a deep notch, the ischium being continued 

 backwards as a sharp spine along the pubis ; pubis projecting far beyond ischium. 



CATHART^. 



C. Postacetabular ilium shorter than ischium, and much deflected ; ischium never 



produced backwards into a spine ; pubis often vestigial ACCIPITRES. 



xi. EXPLANATION OP THE PLATES. 



Plate XXXI. 



Ventral Aspect of the SJcull. 



Fig. 1. Skull of CatJiaristes tiruhii, showing the type of desmognathism peculiar to 

 the Catharhe, wherein the palate is bridged by the union of the horizontal 

 plate of the nasal septum with a pair of septo-maxillary spurs. Note also 

 the presence of basipterygoid processes. 



Fig. 2. Skull of Ulanits cceruleus. The palate is schizognathous. Herein the 

 maxillo-palatines have in.creased in size, whilst the septo-maxillary spurs 

 have completely disappeared. The nasal septum is more complete than in 

 CatJiaristes and may ha seen lying in the middle line of the anterior palatal 

 vacuitj% Above the inflated region of the maxillo-palatines it sends down- 

 wards a feeble pair of spurs which nearly toiich the niaxillo-palatines. The 

 basipterygoid processes are represented only by a pair of minute prickles. 



Fig. 3. ^'k\x\\ oiFal CO minor. The palate is completely desmognathous. Note the 

 peculiar form of the vomer, and its relation to the maxillo-palatines. The 

 antrum of the maxillo-palathies is reduced to the merest vestige. 



Fig. 4. Skull of Circaiitus gallicus. The palate is schizognathous, and an exaggeration 

 of that seen in JElanus. Fusion of the approximated maxillo-palatines 

 and a downgrowth of and addition to the substance of the nasal septum 

 would give the palate of Falco. Note the palatal aperture of the antrum. 



Fig. 5. Skull of Pseudogt/ps hengalensis. The palate is indirectly desmognathous. 

 The palate is bridged l)y the fusion of the greatly swollen nasal septum 

 with the widely separated maxillo-palatines. 



Fig. 6. Skull of Gri/paettis harbatvs. The palate is indirectly desmognathous, and 

 of the same type as in Gfips, but from its less specialized condition shows 

 how the palate of Gyps has been derived. The vomer is present, the 

 maxillo-palatines are of great length and widely separated, whilst the nasal 

 septum can be traced throughout its entire length. 



Fig. 7. Skull of Serpentarivs serpentarius. The palate is schizognathous, since 

 the maxillo-palatines, though closely approximated, do not fuse. Fusion 

 would produce the completely desmognathous type of Falco. The antrum 

 of the maxillo-palatines is of great size, and the maxillo-palatine processes 

 are large. 



Explanation of letters. 

 A.p.v. = anterior palatal vacuity, p.a.a. = palatal aperture of antrum. 

 bp.p. = basipterygoid process. pt. = pterygoid. 



mi:p. = maxillo-palatine process. s. = spur of nasal septum. 



n.s. = nasal septum. vo, = vomer. 



p.a. = palatine. 



