2*6 PROCEEDINGS OP THE CANADIAN INSTITUTE. 



The maxillae are specialized for the support of the long maxillary 

 tentacles. Instead of developing parallel to the axis of the skull, 

 they extend outwards at right angles to it. their antero-posterior 

 extent being very much diminished. They have, in fact, lost all 

 the usual relations to the gape. That they do not possess teeth 

 is not remarkable, since even in Esox they are toothless, though 

 probably their origin was similar to that of the intermaxillae, i.e., 

 the union of cement plates. The fact of their being moved by a 

 special muscle lying below the adductor rnandibulce, instead of by the 

 upper layer of that muscle, and also their relation to a nerve aris- 

 ing from the trigeminus before its division into the superior and 

 inferior branches, which seemed to indicate for them an angular 

 nature, gave rise to a passing idea that they might not really be 

 homologous with the maxilla? of other Teleosts, and I was inclined 

 for a time to compare them to. the supramaxillaries described by 

 Geo-enbaur as occurring in Alepocephalus and Clupea 1 . These pecu- 

 liarities, however, do not properly belong to the bones but to the 

 tentacle, and, since the relations of the bones are the same as those 

 of the maxillse of other Teleosts, and their mode of development 

 similar, there seem to be no reasons for departing from the usual 

 idea that they are homologous with the maxillae of other osseous 

 fishes. 



The palatine bears no teeth. The first trace of bone is formed by 

 the perichondral investment of the ethmo-palatine cartilage, this 

 osseous layer having similar histological characters to the cement 

 plates, there beirg evidently a close relation between these two 

 forms of bone. 



The true pterygoids are all so-called cartilage bones, and therefore 

 the bone described as No. 4 cannot belong to the series. Its true 

 relations have already been indicated. The presence of only one 

 pterygoid is, however, a peculiar feature. In the youngest stage 

 which I was able to study, ossification had just commenced, and by 

 means of sections 2 it was seen that the anterior portion of the 

 metapterygoid contained no cartilage, there being thus, apparently, 

 an interval between the anterior extremity of the pterygo-quadrate 



iLoc. vit. 



* I must testify to the good results obtained by the use of a saturated watery solution of Bis- 

 marck Brown. Not only are cartilage and bone admirably differentiated, but also muscle, 

 nerve, glandular tissue, etc. 



