516 E. TULLEY NEWTON ON THE REMAINS OF 



extending to its lower margin, there are pitted plates similar to those 

 last mentioned, but without the radiating ridges (fig. 8, c). This 

 dental armature of the " basibranchiostegal " is most likely of the 

 same nature as that mentioned by Cope as occurring upon the inner 

 surfaces of the ceratohyals of a P. lestrio, and is to be compared to the 

 minute teeth found upon various parts of the mouth in the pike and 

 other fish ; but it is certainly peculiar to find it so far down upon 

 the sides of the bone, which, it would seem, must have stood up in 

 the floor of the mouth as a prominent crest between the hyoid 

 bones. A dried specimen of the branchial arches and tongue of 

 a Tunny, preserved in the Museum of the Royal College of Surgeons, 

 shows similar plates very distinctly. 



Palato- quadrate arcade. — Parts of the anterior and posterior ex- 

 tremities of this series of bones are preserved in the present spe- 

 cimen. Lying across the left ceratohyal there are portions of two 

 bones (PL XXII. fig. 1, qu and pt). The front edge of the one 

 marked pt is a natural free margin ; its posterior portion underlies 

 the second bone qu, and is partly united to it by a dentate suture. 

 The upper, lower, and hinder margins of the second bone qu are 

 broken ; and inferiorly it shows the commencement of a sudden 

 thickening. In all probability these bones are parts of the pterygoid 

 and quadrate bones, and the thickening of the lower portion of the 

 hinder one is really the commencement of the articular condyle. 



The front portion of this arcade is represented by the greater part 

 of the palatine bone (PI. XXII. fig. 2 pi), which has that peculiar 

 conformation of its anterior part termed by Prof. Cope the " mal- 

 leolus;" this has a smooth surface above for articulation with the 

 prefrontal, and another below for articulation with the maxilla. A 

 small rugose surface upon the outside of the malleolus appears to 

 have formed part of the external facial surface ; but, with this ex- 

 ception, the palatine bone was covered by the suborbital bones, 

 parts of which are still to be seen. The hinder part of the palatine 

 is broken off; but so much as remains lies close upon the upper 

 margin of the maxilla. Internally it is partly hidden by a pitted 

 bony plate, to which many minute teeth are still attached. 



Ethmoidal region. — This is represented by a mass of bone which 

 it would have been extremely difficult to determine, but that it 

 retains a surface for articulation with the right palatine, and has 

 fixed to its front portion fragments of the anterior articulations of 

 both maxillae. These landmarks not only show the nature of this 

 bony mass, but also allow its relation to the bones just mentioned to 

 be clearly made out (eth. &c. fig. 2). The sutures between the 

 various parts are so obscure that little can be said as to the form of 

 the constituent bones. There are portions of both prefrontals, the 

 vomer (?), ethmoid, possibly a part of the parasphenoid, fragments of 

 the maxilla;, and of certain dermal bones. The prefrontal appears to 

 have been perforated for the passage of the olfactory nerve (olf). 

 The bone which is referred to the vomer has no traces of teeth upon 

 it ; and it may be that it is the front part of the parasphenoid 

 (fig. 3, vo). 



Brain-case. — Certain bones forming part of the brain-case were 



