GREGORY: FISH SKULLS 



403 



the roof of the cranial vault, where it lay beneath two of the enlarged dorsal fin spines. 

 In many of the higher ceratioids the supraoccipital becomes dominant as a large round 

 plate, while the parietals disappear and the epiotics become greatly expanded. Occa- 

 sionally, however, as in Haplophryne hudsonius Beebe (Fig. 280) and in Rhynchoceratias 

 longipinnis (Parr, 1930c), good-sized but thin parietals are retained. In these cases we may 

 well suspect a sporadic reappearance of a variable or dormant character, rather than an 

 independent derivation from very ancient ceratioid types, as suggested by Parr (1930c, p. 5.) 



Lasiognathus sp. 



Fig. 275. Lasiognathus. From stained preparation by Mfss Gloria Hollister for Dr. William Beebe. 



The lUicial trough, already pronounced in Antennarius (Fig. 2655) forms a promment 

 feature in ceratioids. It represents a caving~in of the skull-roof due to the presence of the 

 enlarged basal bone of the illicium and of the usually strong muscles, arranged in three pairs, 

 which are attached to it. Tate Regan has shown (1926) that in more advanced ceratioids, 

 such as the Ceratiidae, this trough forms a deep groove extending back on the roof of the 

 occiput and lying between the raised epiotics. 



Regan's figures of the skull-tops of ceratioids show great contrasts in proportion be- 

 tween the very wide skull of Melanocetus johnsoni and the very elongate skull of Crypto- 

 sparas. In the relatively primitive skull of Borophryne apogon {op. cit., Fig. 8) the arrange- 

 ments of the lateral ethmoid, mesethmoid, interfrontal fenestra and of the bones on the roof 

 of the cranial vault all seem readily derivable from the antennariid type. The vomer, 

 however, has become excessively small, while in Melanocetus it is very wide. The meseth- 

 moid is very small in Melanocetus, very long and large in Gigantactis. Thus the bones 

 reflect the great differences in the adjacent soft parts. 



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