554 H. H. SWINNERTON. 



the absence of a well-markecU'Ostrnm ; hence the pre-palatine 

 articnlation (fig. 51, j^af) is situated at its anterior extremity, 

 and, as in the pike, the facet is not specialised. 



Both in the young- (Text fig. 2) and adult Belone (fig. 49) 

 precisely the same conditions prevail; indeed, in one small 

 individual the palatine and pre-ethmoid cartilages were even 

 fused together. The region of this is indicated by the dotted 

 line in fig. 49 (pa.'). The palatine (pa.) bone is simple in 

 shape, lacks a maxillary process, and is edentulous ; poste- 

 riorly it sends a lamina of bone along the outer side of the 

 palatine cartilage {qu. iia.) to meet a similar process from the 

 quadrate [qn.). Thus the ectopterygoid is functionally 

 replaced and is absent. The cartilage itself, which never 

 breaks down though exposed dorsally, does not enlarge at 

 any point to form a post-palatine articulation. The ethmoid 

 is predominantly cartilaginous, and in the absence of a well- 

 developed rostrum is of the same type as that of the pike, 

 but is much shorter. 



The condition in Esocoetus is identical. 



While the almost wholly cartilaginous condition in the 

 Belone is the retention of a primitive condition, the greatly 

 ossified palato-ethmoid region of Syngnathus is at the 

 opposite extreme of specialisation (fig. 50). The palatine 

 bone (pa.) has the same characters as in the stickleback, 

 and like that is partially enclosed posteriorly by the single 

 pterygoid (c.) (McMurrich, 83). Tlie ethmoid region when 

 compared with .that of young Siphonostoma (fig. 48, e.) is 

 seen to owe its great length to elongation, not of the hinder 

 half, containing the mesethmoid cartilage, but to that of .the 

 fi'ont half, consisting purely of ethmoid plate. Nevertheless 

 the mesethmoid bone (fig. 50, e. m.) has apparently extended 

 quite to the anterior end (McMurrich, 83), including the pre- 

 ethmoid cornu. The palatine bone (pa.) which is attached 

 to the pre-ethmoid cornu (pa.') between the mesethmoid bone 

 and vomer is carried too far forward for it to bear any 

 relationship to the parethmoid bone {c ]>• &•)• 



Fistularia differs from Syngnathus only in the fact that 



