360 MR. W, p. PYCRAPX — CONXKIBUTIONS [Apr. 9, 



The Maxillo-jugal Arch. 



The maxilla, in the skulls now under analysis, presents features 

 of unusual interest, inasmuch as this element of the jaw retains 

 more primitive chai-actei-s than are to be met with among the 

 remaining Oscinine Passeres. My examination of this bone must 

 begin with the Tyrannidte. Though in the adult the extent of the 

 maxilla cannot be determined, the palatine process thei-of forms a 

 large triangular plate with its apex cui-ved backwards in a semi- 

 circle, almost meeting the free, anterior, end of the vertical 

 descending, scroll-shaped plate of the palatine (text-fig. 102 Ij, 

 ■mx.p.) and underlying the free end of the vomer. 



In the Pittidfe this maxillo-palatine plate has perhaps preserved 

 even more of its original shape, since it is larger and less pointed 

 at its apex (fig. 102 d, mx.p.). 



The Muscica-pidse present the early stages of transition which 

 eventually produced the type of maxillo-palatines met with in the 

 higher Passeres. In Newtonia these processes are broad, strap- 

 shaped, and deeply pitted below by a pneumatic foramen, while 

 their direction is backwards. In Terpsiphone the maxillo-palatine 

 processes are long and narrow, and spring from a broad shelf of 

 bone which passes forwards into the palatine process of the pre- 

 maxilla ; and the same is true of Piezorhynchus. In Muscica2)a the 

 final stage is reached : the maxillo-palatine being reduced to a long, 

 slender, curved bar springing from a rod-like base. The free end 

 of the process almost touches the free end of the descending 

 vertical scroll of the ventral aspect of the palatine. 



The Campopha,gid8e closely resemble the Muscicapidse in the 

 form of the maxillo-palatine process ; it appears to differ chiefly in 

 that it is relatively shorter than in the Muscicapidse. 



Among the Laniidfe, as at present constituted, this region of 

 the palate presents two strongly contrasted phases of development. 

 In the less specialised Laniince, e. g. Lanius, Laniarius, and 

 Dryoscopus, the maxillo-palatines do not differ essentially from 

 these elements in the Campophagidpe, a large palatal vacuity 

 bounding these processes in front. But in Gorvinella the an- 

 terior palatal vacuity is partly filled up by the ossification of 

 the vestibular floor. The Prionopidfe and the Dicruridse agree 

 with Corvinella in this respect. The Gymnorhinse, included by 

 Dr. Sharpe with the Laniidfe, differ markedly from the Laniinse 

 in this matter ; and this on account of the ossiflcation of the 

 vestibular wall and nasal septum already referred to (p. 358). 



In Pityriasis and Gymnorhina the anterior palatal vacuity is 

 closed, in part by the ossified floor of the vestibulum, and in part 

 by the nasal septum, so that only a small pit is left in front of the 

 vomer. The Artamid?e and Yangidee in this matter agree with 

 the Gymnorhinse. The palate of the aberrant Erocharis 

 {Euryceros) in many respects recalls that of the Gymnorhinfe 

 (p. 359) and Artamidfe, but it difiers in that the maxillo-palatines 

 in front of the maxillo-palatine processes are inflated, forming a 



