27 
panding to form the head, which is capped with cartilage. 
The head has 4 articulations: (1) It is closely attached 
above to the large unpaired intermaxillary cartilaget 
(7.M.C.), to which on its other side the left maxilla is also 
attached ; (2) ventrally the maxilla is capped by a move- 
able piece of cartilage, much smaller and situated ventral 
to the inter-maxillary. This moveable or gliding car- 
tilaget works in the groove to the right of the beak-like 
mesethmoid prominence (cp. fig. 1), and also over the 
large convex facet on the right side of the head of the 
vomer. It is connected with the inter-maxillary and is 
excavated on both surfaces to receive the head of the 
maxilla and the vomerine facet. The latter or free exca- 
vation is so contrived as not to interfere with the move- 
ment of the cartilage above the vomer. The reader who 
consults a dried cranium of the Plaice when reading this 
description will understand that the movement permitted 
to the maxillary bones by these facets and gliding car- 
tilage is an oblique dorse-ventral one- in the direction of 
the eyeless side (cp. Traquair op. cit.). This explains the 
well-known fact that Plaice are able to pick up food lying 
on the sea bottom by twisting the mouth towards the lower 
or eyeless side. In other Pleuronectidee the twisting of 
the mouth is towards the ocular side ; (3) dorso-posteriorly 
the maxilla, as already pointed out, is connected by liga- 
ment with the anterior extremity of the palatine; (4) 
anteriorly and externally it is deeply excavated for the 
reception of the pre-maxilla. The anterior edge of the 
maxilla is close to and partly overlaps the pre-maxilla. 
Pre-Maxilla (?.1/7.)—Forms the dorsal part of the 
gape and consists of two arms. Its vertical arm forms the 
gape and bore 4 teeth in the specimen now described, 
{ We follow Traquair in using this term for the cartilage in question. 
+ Cp. Traquair, Trans. Linnean Soc., London, xxy., 1865. 
