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TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY 



All the bones of the preorbital face in the side view also differ widely in proportions, 

 sometimes even in rather closely related genera, as in the short-faced Lophodolus (Fig. 274) 

 and the very long-faced Lasiognathus (Figs. 275, 276). 



Of the family Oneirodidse, in which, according to Regan, the illlcial trough extends the 

 whole length of the upper surface of the skull, the most primitive-appearing forms (Fig. 277) 

 are Dolopichthys luetkeni and D. dance. The former seems to be well fitted to give rise to the 

 Melanocetidae, the latter to forms that culminate respectively in Lasiognathus, with a very 

 long skull, and Lophodolus, with a short deep one. The skulls (Figs. 274-276) of these 



LaSiogna^hus 



Fig. 276. A. Lophodolus. B. Lasiognathus. Top views. From stained preparations by Miss Gloria Hollister for 



Dr. William Beebe. 



forms (which I have had the privilege of studying in Doctor Beebe's laboratory) conform 

 in all respects to the family characters of the Oneirodidae as defined by Regan, and show a 

 remarkably close agreement in the relations of all parts of the opercular, branchiostegal, 

 hyoid and other series. 



The Ceratiidae, according to Regan, are related in skull structure to the Oneirodidae but 

 the different species differ from Dolopichthys in retaining either a well developed or a 

 vestigial second dorsal ray. The Gigantactinidae, according to Regan, are related to the 

 Ceratiidae; their enormously elongated illicium is supported by enlarged mesethmoid and 

 lateral ethmoids. 



The Melanocetidae, according to Regan, are also "evidently related to the Oneirodidae." 



