134 ■ ME. W. p. PYCRAFT OX THE OSTEOLOGY [Feb. 20 



ii. The Skull of tub Adult. 



The skulls of the types which form the subject of this paper 

 present no striking peculiarities or extremes of specialisation 

 such as are met with among the Eury]a?micla?. Yet collectively 

 they conform to one general plan distinguishable from that of the 

 Tyrannidfe and the forms which appear to me to be allied thereto. 

 This plan, and the modifications thereof, I hope to be able to 

 describe in the near futui-e. 



The skulls of the Ti'acheophone Passeres, and the forms herewith 

 associated, are to be distinguished from those of the Tyrannida?, 

 Pittidje, and PhilepittidjB mainly on account of the absence of an 

 ossified nasal septum ; but besides these there are other small 

 characters, or combinations of characters, too subtle for tabulation, 

 but which nevei'theless contribute towards the delimitation of the 

 several groups. Taken separately, however, the skulls of the types 

 herein described can readily be distinguished from those of the 

 Tyra uniform types. But, as will be shown in the sequel, the 

 ai-rangement I here propose does not rest on these characters 

 alone. 



The following ai'e the characters which distinguish the families 

 which come within the scope of the present paper : — 



Pipridce. — With a nasal hinge ; inflated antorbital plates ; a free 

 lachi-ymal ; maxillo- palatine xiphoid ; vomer short and broad ; 

 postorbital process obsolete ; pi-ocessus zygomaticus spine-like 

 and blunt ; interorbital septum perforated. 



Formicariidce. — With anterior nares enclosed by a Ijony wall, 

 leaving a wide aperture at the proximal end of the nasal fossa 

 between the premaxillary and descending processes of the 

 nasal. Maxillo-palatines strap-sliaped, crossing the hinder 

 end of the olfactory fossa, and passing backwards beyond the 

 level of the median, descending plate of the palatine ; vomer 

 long and broad ; postorbital process large, sometimes joining 

 the pi'ocessus squamosi ; intei'orbital septum perforate. 



Bendrocolaptidie. — Interorbital septum imperforate ; nostrils occa- 

 sionally of Formicaroid type ; jDostorbital process small ; 

 maxillo-palatines short and Ijroad, crossing the hinder end of 

 the olfactory fossa and terminating immediately in fiont 

 of the descending plate of the palatine ; vomer short. 



Syncdlaxidm. — Nostiilsschizorhiiral ; interoi-bital septum perforate ; 

 maxillo-palatine of great length and slenderness and con- 

 tinued backwards to or beyond the level of the fx^ee end of 

 the median descending plate of the palatine. 



Conojiojjhagidce. — Interoi'bital septum wanting ; postoi-bital pro- 

 . cesses wanting; maxillo-palatines long, narrow, and anga- 

 lated, continued backwards to the level of the median 

 descending plate of the palatine. 



Hylaci%d(x. — Interorbital septum j^erforate ; postoi-bital processes 

 small, placed low down on side of skull ; maxillo-palatine 

 lonor and slender ; vomer short, long limbs. 



