1 6 WATSON & Day, Notes on some PalcBozoic Fishes. 



its individuality. In any case, these bones, instead of the 

 row of small teeth which they support in Glyptopomus, 

 carry powerful fangs, three of which are visible in the 

 specimen. This specimen is further of importance because 

 it shows the hyomandibular. This bone, although of 

 quite large size, seems to be extremely feebly ossified, the 

 bone forming a mere skin. It articulates with the special 

 process of the otic region of the chondrocranium which 

 we have described, passes backwards behind the posterior 

 border of the pterygoid, and then is either suddenly bent 

 at right angles so that its lower half is directed forwards, 

 or terminates, the lower half being a separate bone. In 

 any case, the lower termination of this bone, whatever be 

 its nature, rests on the pterygoid, where it sheaths the 

 quadrate just above its lower edge. This specimen on 

 both sides exhibits a foramen of medium size, which 

 pierces the hyomandibular just below its head. 



Two specimens give evidence of the presence of an 

 elaborate series of hyoid arches apparently entirely carti- 

 laginous in structure, but do not allow us to give any 

 description. 



In Rhizodopsis we have been unable to see any 

 specialised post-temporal but the supra-clavicle is a large 

 bone of ovate shape whose lower and hinder end passes 

 on to the visceral surface of the clavicle. 



The clavicle is a very large bone consisting of two 

 rami one of which stands vertically being exposed on the 

 flank of the fish behind the operculum and sub-operculum, 

 whilst the other passes forward and downwards behind the 

 last lateral gular until it is overlapped by the small infra- 

 clavicle. There is some evidence of a feeble ossification 

 in the cartilaginous shoulder girdle, and the proximal 

 element of the fin is well, though superficially ossified. 



The Knowles Ironstone specimens being compara- 



