38 MR. Wi p. PtcftAFT ON THE [May 2, 



broad limbs indistinguishably welded with the palatines, agreeing 

 in this with Calyptomena and Cymhirhynchus. 



The palatine (PL 11. fig. 2 «) in GalyjAomena is a long bone : 

 anteriorly rod-shaped, it extends backwards as far as the 

 under surface of the antorbital plate, when, after sending out- 

 wards a prominent, rounded elbow — "transverse bone" — it turns 

 abruptly inwards, ultimately forming a roughlj' spatulate plate, 

 bent upon itself so as to form a long linear surface running along 

 the parasphenoid rostrum, and fusing mesiad with the vomer and 

 a free downwardly hanging curtain to form a cavernous space in 

 the roof of which is the base of the vomer. 



The palatine of Chasonorhynchus differs from that of Calyj^to- 

 mena in the greater width of the hinder laminated portion and the 

 more extensive development of the inferior free edge, forming the 

 cavernous sjoace beneath the vomer. This edge now appears 

 rather as a shelf -like projection developed from the inner border 

 of the shaft of the palatine. 



In Cymhirhynchus the palatine shaft is broaxler than in 

 Ccdyptoiniena^ and this increased breadth is especially noticeable 

 at its junction with the body of the premaxilla. The latter, as 

 has already been pointed out, is much more conspicuous than in 

 Ccdyptomena and terminates in a doubly crescentic free edge 

 synchronously with the palatines. Thus a relatively enormous 

 oblong space is enclosed. In Gory don these features are still 

 more exaggerated, the " elbow " is also more strongly marked. 



In broadness and the truncated form of the shaft of the 

 palatines, the more specialised Eurylsemidae recall the Podargidee, 

 wherein the body of the premaxilla is still more developed and the 

 truncation of the palatine distally more marked. Both in the 

 specialised Euryleemidpe and the Podargidas the truncation of the 

 vomer appears to have been brought about to facilitate the move- 

 ments of the nasal hinge, which in both types lies immediately 

 above the anterior ends of the palatines, while in the more 

 generalised Calyptomena^ which lacks a nasal hinge, the palatines 

 run far forwards. 



The pterygoid in Calyptomena (PI. II. fig. 2 a) is a long, 

 slender, rod-shaped bone, laterally compressed, and perforated by 

 a pneumatic foramen at its articulation with the quadrate. At 

 its anterior end it meets its fellow of the opposite side in the 

 middle line ; and immediately sends upwards and foi'wards a sub- 

 crescentic plate which, embracing the parasphenoidal rosti'um by its 

 plane surface, affords attachment along its inferior border to the 

 vomer. Late in life the articulation with the vomer is succeeded 

 by anchylosis. Certain points concerning the morphology of the 

 end of the pterygoid will be discussed in the section dealing with 

 the nestling skull (p. 43). 



In Chasmorhynchus the anterior ends of the pterygoids do 

 not meet in the middle line but impinge instead directly against 

 the parasphenoidal rostrum, foi-ming therewith a ptedate articu- 

 lation, which is lai'gely augmented by " hemipterygoid " elements 



