550 H. H. SVVIN NEKTON. 



the majority of Teleosts the metapterygoiJ abuts directly on 

 the quadrate, but here it is separated by a wide space, partly 

 occupied by the pterygoid boue, and this is, no doubt, largely 

 due to the forward shifting of the quadrate. In Belone the 

 two bones (fig. 49, qu. and p. gr. 771..) lie one against another; 

 and, as the suture between them is cartilaginous, it gives an 

 indication of the original weakness of the metapterygoid 

 cartilage — an indication all the more trustworthy because the 

 laminar outgrowth of this bone is suturally connected with 

 the pterygoid and not with the quadrate, which has no such 

 extension dorsally. These relations seem to be the prevalent 

 ones, so tliat the length of the suture between the metaptery- 

 goid and quadrate may generally be taken as indicative of the 

 extent of the original cartilage. If so, then in pike (fig. 43), 

 Zanclus (fig. 52), Balistes (fig. 53), and other Plectognathi, the 

 Acronuridge, CypriuodontidcB, and the great majority of 

 Acanthopterygii, the cartilage was strongly developed ; as 

 opposed to its marked reduction in Belone and Gasterosteus, 

 and its complete suppression in Syngnathus and Siphonostoma. 

 In the adult of the last two forms, as well as of Fistularia, 

 all the bones of this region, including the quadrate, have 

 sent out extensive laminje to form the side walls of the 

 tubular snout, so that only the study of ontogeny can show 

 the ti'ue distribution of the original cartilages. 



The palatine bone {'pci.), as already described, appears as 

 an ossification of the palatine cartilage around and behind 

 its connection with the ethmoid. As in Siluroids (Pollard, 94, 

 p. 355), the continuity between these two cartilages becomes 

 lost with advancing ossification; but the bone still articu- 

 lates with the pre-ethmoid cornu. The outer surface of its 

 anterior half appears in a lateral view of the head skeleton 

 (fig. \1 ,'pa.) as a sculptured bone lying between the nasal and 

 the first bone of the suborbital series (sa.i), and bears such a 

 close resemblance to the pre-orbital bone (antorbital, Sagemehl) 

 of Amia that one would be almost forced to acknowledge its 

 homology with that if one did not already know that Amia 

 possessed a palatine bone. The resemblance is all the more 



