396 MR. w. p. PYCKArx o>r the [Mar. 21, 



borders are straight, its posterior border is V-shaped. It does 

 not extend forward beyond the level of the anterior 5 of the 

 vertically elongated squamosal. Its outer posterior border runs 

 from the angle of the lower j of the squamosal (PI. XXIII. fig. 1) 

 inwards to the upper half of the lateral border of the supx'a- 

 occipital ; its inner posterior border is in part approximated to 

 but not yet fused with the supraoccipital, and in part free, 

 bounding, with its fellow of the opposite side, the parieto-occipital 

 fontanelle, as the supraoccipital bounds it ventrally. 



The frontal is broadest posteriorly. Its mesial and posterior 

 borders are straight. The latter, skirting the parietal posteriorly, 

 sweeps forwards to the inner side of the squamosal, to articulate 

 with the alisphenoid (PL XXIII. fig. 1). The free outer border 

 is grooved for the supraorbital gland. The region above the 

 alisphenoid constitutes the orbital plate of the frontal and is of 

 small extent. 



The squamosal is crescentic in form, the concave border for- 

 wards. The tip of the upper limb is free and bounds the supra- 

 orbital groove posteriorly, furnishing the squamosal spines, so 

 conspicuous in the species from which this description is taken, 

 Pelecanoides and Gymodroma. The lower limb furnishes the 

 squamosal prominence. It is almost entirely excluded from the 

 inner wall of the skull. 



The nasal is of great size, and conspicuously convex dorsally. 

 It forms the outer roof of the large olfactory cavity. Beneath it 

 lies the horizontal plate of the mesethmoid. Its posterior end 

 is embraced on either side by the frontal. It is deeply notched 

 forwards to form the anterior and external nasal processes. 

 These constitute the posterior boundary of the narial aperture, 

 which is holorhinal. 



The lachrymal does not differ from that of the adult, p. 387. 



The premaxilla has fused completely with the maxilla, even in 

 the youngest of the two skulls. The nasal process yet, however, 

 remains distinct. 



Th&jugal and quadrato-jugal can only be imperfectly distinguished 

 one from another and from the maxilla, which differs in no 

 important particular from that of the adult. 



The relations between the vomer, palatines, and pterygoid recall 

 those between these elements in Rliea (PL XXIII. figs. 3, 4). 



The vomer consists of a pair of elongated, flattened larainas 

 united in the median line anteriorly. The free posterior ends are 

 received by the concave anterior borders of the hemipterygoids, 

 and are bounded, on either side, by an inwardly turned scroll 

 of bone from the dorsal border of the palatine. 



The palatine is still free, its anterior end is traceable nearly as 

 far forwards as the tip of the jaw. Posteriorly it develops a 

 strong dorsal keel which eventually turns inwards and forwards 

 to embrace the posterior lateral border of the vomer. 



The pterygoid is rod-shaped, and continued forwards to 

 articulate with the vomer by means of a large hemipterygoid. 



