136 Proceedings of the Royal Physical Society. 



another well-known dentigerous bone, which is indisput- 

 ably the maxilla, and closely resembles in form the maxilla 

 of Magalichthys. To all appearance it would also seem to be 

 distinct from the mandible, the margins of which " are nearly 

 parallel," and which displays, besides a large laniary tooth in 

 front, " three or fonr others placed along the ramus, in a line 

 within the small teeth." 



With the bones described by Messrs Hancock and Atthey 

 as the prsemaxilla, maxilla, and mandible of Ehizodopsis, 

 every student of carboniferous ichthyology must be familiar. 

 The interpretation of the first of these as " prsemaxilla " has 

 been accepted by the Messrs Barkas,* and, so far as I am 

 aware, has remained hitherto unquestioned. ISTevertheless 

 the accuracy of its determination as such was to me a matter 

 of doubt from the first. It is true the bone in question does 

 in some measure remind us of the elongated prsemaxilla of 

 Teleostei of the most specialised type, in which that element, 

 loosely articulated with the front of the skull, extends back- 

 wards so as to shut out the now edentulous maxilla from the 

 edge of the mouth (Perca, Gadus, etc.). But as Ehizodopsis 

 is a Crossopterygian ganoid of the type possessing two dorsal 

 fins and subacutely lobate pectorals, one would naturally 

 expect that its prsemaxillary bones would resemble in form 

 and relations those of its natural allies, whether rhombiferous 

 or cycliferous, in all of which, whose cranial osteology is 

 sufficiently known, each prsemaxilla is comparatively small 

 and short, firmly fixed to the front of the cranial shield, and, 

 in fact, very unlike the bone of Ehizodopsis which has been 

 so interpreted. How to fit this bone into the praemaxillary 

 region was to me somewhat puzzling; and, accordingly, to 

 find it in situ in the head of the fish was an object to be 

 attained, before giving in adherence to the views usually 

 maintained regarding it. 



A short time ago my friend Mr Ward of Longton, to whose 

 liberality in lending specimens from his magnificent collection 

 I am on this, as on other occasions, so largely indebted, sent 



* ''Manual of Coal-measure Palaeontology," by T. P. Barkas (London, 

 1873), p. 24, pi. ii., fig. 61 ; W. J. Barkas in Monthly lievieio of Dental 

 Surgery. 



