6 Mr. A. S. Woodward on some 



exposed from its inferior aspect. The main part of this bone 

 (tig. 1 a) is short, stout, and broad, produced below into a 

 median longitudinal keel, and its basipteiygoid processes 

 {bpt.) are short, with a very coarsely dentated articular end. 

 At the front extremity of the otic region the parasphenoid is 

 abruptly truncated, the keel terminates in a roughened 

 pointed knob (&.), and the element continues merely as a 

 narrow slender median bar across the region of the orbit. A 

 detached example of the same bone in specimen no. P. 6834 

 (PL III. figs. 3, 3 a) may be described in almost similar 

 terms ; but here the basipterygoid processes (bpt.) are turned 

 a little more outwards and the median keel is partly broken 

 away. The inner face (tig. 3 a) shows that this keel was 

 hollow in its deepest portion ; and there is a long median 

 scar for articulation probably with the most anterior elements 

 of the brain-case. A pair of foramina, one on either side of 

 the posterior part of the median keel, seem to pierce the bone 

 and open directly on its inner face. 



Other Specimens. — The three more fragmentary specimens 

 only remain for consideration, and may be dismissed with 

 brief remarks. No. 2 (Leeds Catal.) is interesting as exhi- 

 biting the squamosals with the clearly defined straight occipital 

 border of the skull ; and in this fossil the supraoccipital has 

 a less prominent hinder peak than is observed in the specimens 

 described above. No. 23 (Leeds Catal.) is very much crushed 

 and fractured, but the outline of the left frontal is distinct, 

 and, if appearances be not deceptive, its connexions are 

 different from those in both types described above. Here 

 the frontal seems to meet its fellow of the opposite side for 

 some distance, and the ethmoidal shield is disposed as in 

 no. 1 ; but the hinder part of its inner suture is shaped as in 

 no. 24, and was thus presumably articulated with a median 

 plate much resembling the anterior end of the supraoccipital 

 in the last-named fossil. The third and last specimen is the 

 small group of isolated bones (Brit. Mus. no. P. 6834) of 

 which the squamosal and parasphenoid have been incidentally 

 described above. Among these the right postfrontal (sphe- 

 notic) is specially worthy of notice as being well preserved. 

 It is small and meets the squamosal in a triangular rugose 

 facette ; its smooth outer face is triangular, while its equally 

 smooth anterior face is gently concave, to form part of the 

 hinder wall of the orbital cavity ; inwardly it is roughened 

 for articulation with another otic element ; its posterior aspect 

 takes part in the facette for the upper end of the hyoman- 

 dibular; and its lower extremity shows a coarsely inter- 

 digitating articular surface. A problematical bone from the 



