GREGORY: FISH SKULLS 



207 



salmonoid Isospondyls that retain an adipose fin and such generalized Cretaceous acantho- 

 pterygians as Aipichthys (Smith Woodward, 1912, p. 254). It distinctly approaches the 

 existing scopelid Chlorophthalmus, but is more primitive in several respects (Smith Wood- 

 ward, 1902, p. 33). Tate Regan also (191 1«, p. 120) agrees that Sardinoides crassicauda 

 and illustrans certainly belong to the Aulopidae {cf. Fig. 85), the most primitive of the 

 existing scopeloids, with which they agree closely in skull structure. On the whole, the 

 skull characters of Sardinoides and Aulopus are very primitive. The mouth is fairly large, 

 bordered with fine teeth, which however do not extend to the maxillary. The latter bears 

 two supramaxillz, a very primitive character. The parietals, although short antero- 

 posteriorly, meet in the mid-line and exclude the small supraoccipital from contact with the 

 frontals. The orbitosphenoid is well developed, all the opercular bones are present and 

 it is only in minor details that the skulls diflFer from those of such primitive isospondyls as 

 Elops (Regan). The subopercular forms the border of the gill cover. 



parelh suporb 



deth „ 



Saurusindicus 



Synodus foetens 



Fig. 86. Synodus foetens. 



Synodus. Synodus (Fig. 86) and its allies are more specialized than Aulopus in the 

 backward inclination of the suspensorium, with the presence of more or less laniary clus- 

 tered teeth. In Synodus foetens, according to Starks (1926^, p. 155), the vomer is entirely 

 absent as it is also in the allied Trachinocephalus myops (Fig. 87), whereas in Saunda 

 argyrophanes, which is very much like Synodus in other respects, the vomer is well developed 



A very comprehensive and thorough analysis of the osteology of the Iniomi with 

 special reference to the phylogenetic relationships and divergent trends of the families was 

 published by Parr in 1929, from which the following passages may be quoted: 



"The line of diflFerentiations leading from Chlorophthalmus through Bathysudis to the 

 Omosudids is characterized by a strong reduction of the lateral ethmoids, with complete 

 obliteration of their transverse process and a corresponding shifting forward of the main 

 attachment of the palatines to the naso-ethmoidal region. Further, by the reduction of the 

 suborbital bones and by the anterior fusion of the nasals with the mesethmoid. The 

 parietals remain separate. The posterior temporal fossa are entirely unroofed. There is 



