GREGORY: FISH SKULLS 



211 



In the Scopelarchidse [Fig. 90] and Evermannellidae [Fig. 91] the suborbital bones are 

 strongly developed, instead of reduced, and a posteroventral production of the infraorbital 

 along the upper margin of the maxillary has appeared. The lateral ethmoids and their 

 transverse processes for attachment of the palatines are well developed throughout the 

 series. The nasals remain entirely separate from the mesethmoid, being only attached by 

 ligament to the anterior margins of the frontals. The parietals have become completely 

 fused to the frontals. This is, as far as our knowledge goes, an entirely unique feature 

 among the Iniomi. A fundamental difference is finally contributed by the fact that the 

 Scopelarchidse and, to some extent at least, also the Evermannellidae, show a distinct and 

 well developed roof over the anterior parts of their posterior temporal fossae. According 

 to Regan's description this roof has already disappeared in Chlorophthalmus and no traces 

 are found in any of the Sudldae and Omosudidae examined by the author. As the feature 



pfr^ 



Fig. 92. Crtomimus regani. .After Parr. 



is presumably to be regarded as a primitive character, the Scopelarchidse can therefore 

 not be derived from a Chlorophthalmus-Vike ancestral type, and the various features of 

 specialization exhibited already by the most primitive forms of the Scopelarchus-hranch 

 (parietals fused with frontals, etc.) make it equally impossible to derive Chlorophthalmus 

 from a Scopelarchus-Vike ancestral type. The two phylogenetic sub-branches of the Iniomi 

 now under discussion must therefore have separated before the stage of either of these 

 two primitive types had been reached, as shown in the diagram on the opposite page. . . . 

 "The family Cetomimidae [Fig. 92] comprises a group of highly diflterentiated or 

 degenerate deep-sea forms, which, in spite of their degeneration, carry evidence of similar 

 fundamental phylogenetic tendencies as those expressed in the skeletal structures of the 

 Scopelarchidje. They thus agree with the latter family in having the parietals fused with 

 the frontals and in having the lateral ethmoids strongly developed, with prominent trans- 

 verse processes serving as main support and attachment for the palatines. The author is 

 therefore, particularly on account of the first mentioned of these features, inclined to regard 

 the Cetomimidae as derived from the same root as the Scopelarchidae, and it may be added 

 that the general aspect of the skull and visceral skeleton seems to offer no obstacles to this 

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