MORPHOLOGY OF TELEOSThJAN HEAD SKELETON. 551 



striking, because of tlie presence of several sensory papillas 

 (fig. 31) on the skin which overlies it. 



The cartilage which the pterygoid enclosed has disappeared, 

 not because of the encroachments of ossification, as in the 

 parethmoid (Hg. 32, e.p. 6.), but because of actual reduction, 

 as in the case of the supra-orbital band and the hinder portion 

 of the trabeculge. 



The relation of the palatine and pterygoid bones and 

 adjoining cartilages to the ethmoid region in Teleosts is of 

 great importance, and a closer study of it will be found 

 extremely useful in the attempt to ascertain the inter-relation- 

 ships of these fishes. 



For this purpose no fish presents so instructive a condition 

 and so convenient a starting-point as the pike (fig. 43). In 

 it the palatine is a long and massive bone, formed, as in the 

 stickleback, by ossification of the distal portion of the palatine 

 process. At its extremity it bifurcates slightly, and partially 

 encloses the pre-ethmoid cornu with its ossification. Behind 

 this bifurcation, and on the outer side, it presents a rough 

 facet, with projecting upper border {pa. ni.) for the insertion 

 of the inner end of the maxilla. The whole of its ventro- 

 internal surface is armed with numerous powerful teeth. For 

 a short distance behind this the original cartilage persists, 

 enclosed by the ectopterygoid externally and the entoptery- 

 goid internally. Opposite the parethmoid cornu this cartilage 

 enlarges considerably, and offers a well-developed concave 

 surface for articulation with, or more accurately, for sliding 

 on, the rounded ventral surface {pa-") of the cornu. Thus 

 in the adult, as in the larva, there are two points for attach- 

 ment of the palatine process to the ethmoid, a pre-palatiue 

 and a post-palatine. 



In ScoMBEE (fig. 44) the same condition exists, but the 

 parts are more specialised. As in the pike, the palatine bone 

 (pa.) is massive and dentigerous, but here the anterior 

 extremity of the bone is prolonged into a well-developed, 

 curved maxillary process {pa. m.). Internally to the base of 

 this IS a facet, which fits on to and forms a typical articula- 



