22 Mr. W. P. Pycraft on the 



takes place in the latter and in some Passeres, lias resulted 

 from fusion between a sometime free pterygoid and palatine, 

 which articulated by a flexible joint formed between the 

 pterygoid shaft and the segmented extremity of that bone 

 and the palatine. This anchylosis took place when the 

 movement between pterygoid and palatine became too re- 

 stricted to allow of free movement between the two boues. 

 In other words, the unsegmented pterygoid of the forms in 

 question is not a primitive condition, but has been derived 

 from the fusion of a segmented pterygoid such as obtains in 

 the majority of the Neognathse *. 



The style-shaped maxillo-palatines of Zeledonia represent 

 an undoubtedly specialized condition. In the typical Turdi- 

 form palate — e. g. Merula, Cossypha — these structures are 

 larger, spoon-shaped, and inflated at the free end to form a 

 kind of pocket. The spoon-shaped plate underlies the body 

 of the vomer. The linear form seen in Zeledonia is obviously 

 a degenerate condition of a maxillo-palatine of the type 

 found in Erithacus or Sialia, for example. Here these 

 elements are rod-shaped, and much inflated to form delicate 

 shells of bone open along the outer side. Phylloscopus and 

 Anthus shew the Turdiform type. 



V. Summary. 



As to the precise position of Zeledonia I regret that I can 

 say nothing definite until I have had an opportunity of 

 examining much more material than is procurable at present. 

 Before any sound deduction can be framed on this particular 

 question it will be necessary to obtain examples in immature 

 plumage and a series of birds for dissection. The specimen 

 submitted to me for the purpose of this paper was not well- 

 preserved, and, furthermore, was so much damaged that 

 reliable data on many questions concerning the soft parts 

 were impossible. Quite as necessary are examples of other 

 species allied to Zeledonia. 



* Pycraft, "On the Morphology of the Palate in the Neognathce,'" 

 Journ. Linn. Soc, Zool. xxviii. p. 333. 



