274 PEOFESSOE W. K. PAEKEE ON THE 



by their maxillo-palatine process. This region of the maxillary, which in Mammalia 

 and Crocodiles forms so much of the great " hard palate," in the Grosbeak is the frailest 

 of all bony structures (figs. 1 & 2, mx.p) : their use in this bird is to contain a most 

 minute globule of air from the naso-palatal labyrinth. Arising from the supero-internal 

 face of the bone as a fine arcuate filament, they gradually widen ; and in widening they 

 become scooped below. They then become bowed backwards as well as inwards, nearly 

 meet below the vomer, and have two fifths of their scooped part closed in so as to form 

 a microscopic test-tube, which, however, is irregular in form and fiattened from above 

 downwards. 



The vomer is Passerine in the highest degree (figs. 1, 2, v). It is ox-faced in shape ; 

 and the Jiorns and ears are represented by processes of bone that have trespassed upon 

 the nasal wall; the forehead also is seen on the lower face, in front — a triangular 

 thickening ending behind in a keel, and in front forming the sinuous margin of the 

 bone. The vomer is deeply grooved above, and lost in the palatine commissure 

 behind. 



A considerable amount of ossification has occurred in the nasal labyrinth — in the 

 septum most of all, which is sharply segmented ofl" from the mesethmoid, is sharp below, 

 behind ; but its alate part has ankylosed with the rostrum, and runs invisibly into the 

 proximal ossified part of the alse nasi. Both alinasal and inferior turbinals are three 

 fourths bony. The great ethmoidal mass projects above in the same degree as in the 

 Buntings. So also the spongy pars plana {p.jo) is scooped towards the eye, and has a 

 round notch on its outer margin ; but here its " foot " is unusually prolonged, as in 

 those Psittacidse whose suborbital bar is imperfect. In these types, such as Pse- 

 ])hotis multicolor, it is easily seen that a large os uncinatum has coalesced with the 

 pars plana; so it is in Coccothraustes (fig. 1, o.u,i).p); for, although ankylosis has 

 taken place, tlie remains of the suture can be traced. 



Example 52. Skull of an Averdavat {Estrelda astrild). Family Ploceidse. 



Group Oscines. 

 Habitat. South Africa. 



Intensity of ossification, with equivalent ankylosis of independent parts, takes place in 

 this, one of the smallest of the Finches, equally with the Grosbeak, one of the largest. 

 My study of these small southern forms has been in the type given above, in the 

 Crimson Finch [Estrelda phaeton) from Port Essington (Australia), and in the young (as 

 Mr. Sharpe believes) of Habropyga subjlava. In these types the broad strong rostrum 

 is deflected as much as in the Buntings and the Corn-Buntings, and has a high back 

 near the frontal region. For their size the skull is nearly as strong as in the Grosbeak ; 

 but they lack the rimmed orbit. 



Tlie pterygoids are similar, and have a good epipterygoid hook (Plate L. figs. 4 & 5, 

 f-py, pg) ; but in these forms the spatulate end ankyloses with the palatine. In the 



