GREGORY: FISH SKULLS 



409 



the type of Haplophryne hudsonius, the basal bone of which arises from the interfrontal 

 depression precisely as does that of the true illicium of a young Oneirodes; assuredly the 

 assumption that it is not the real illicium in Haplophryne but one of the postillicial rods 

 which has moved forward to take its place, looks forced; (2) Doctor Parr further assumes 



mU'^'^ 



f}fm. 



anff 



cerhypop T^^r-J^^ 



Rhynchoceratias 



Fic. 281. Rhynchoceratias. After Parr. 



(p. 17) that the rostral bone has secondarily disappeared in Haplophryne. The contrary 

 assumption that Haplophryne retains the primitive unossified condition of the rostrum, 

 along with the more primitive rostral denticles, the unexpanded nasal sacs and more nor- 

 mal premaxillae, makes less demand upon our imagination. 



'' Lcevoceratias" Parr (1930f, p. 19) is one of the most remarkable (Fig. 282) of all known 

 pediculates, one which has departed very far from the typical pediculate type. Belonging 



Laevoceratias 



Fig. 282. Lavoctratias. After Parr. 



to a predaceous group (the ceratioids) in which the mouth is typically cavernous, with long 

 piercing teeth, its mouth has become minute and provided with feeble nipping denticles 

 derived from the skin; belonging to a group whose members usually rely upon a highly 

 developed illicium, it has lost all traces of the illicium except its slender basal rod and possibly 

 the rostral denticles; belonging to a group whose primitive members have small olfactory 

 sacs, the ancestors of Leenoceratias evidently first developed such sacs and then reduced at 

 least their external openings. 



