490 Edward Phelps Allis jr., 



The posterior two of these three bones must be squamosal ossicles, 

 representing perhaps the separated facial and postfacial components of 

 that bone. The anterior bone would seem to be either a part of the 

 frontal, corresponding perhaps to the small detached part of the frontal 

 in Alestes nurse, or a postfrontal, this depending on how the inclosed 

 organs were innervated. Pander considered these three bones as ho- 

 mologues of the spiracular, and the pre- and post-spiracular series of 

 bones of Polypterus. But this is certainly an error. Anterior to the 

 bone that I have above considered as being either a postfrontal or a 

 part of the frontal, the sensory canal is continued, dorso-mesial to the 

 orbit, in what must be a supraorbital canal; and the single bone said 

 to be traversed by that canal may be a frontal alone, or a fused 

 frontal and nasal. No postorbital canal is shown in any of the de- 

 scriptions or figures, and this canal is therefore either wholly wanting 

 in this fish, as Herrick concludes it to be in Lophius, or it was re- 

 presented by surface organs, as in Batrachus, those organs naturally 

 having left no trace of their existence. The suborbital canal is shown 

 beginning anteriorly in the suborbital ossicles, and running backward 

 through those ossicles and then directly backward across the preoper- 

 culum, where, in Osteolepis macrolepidotus, it turns downward along 

 the hind margin of the latter bone. That part of the canal that has 

 a horizontal course across the preoperculum would seem to be the 

 homologue of the horizontal cheek line of pit oi-gans of Amia, the 

 vertical portion being the homologue of the preopercular canal. Near 

 the hind end of the parietal. Pander shows and describes what he 

 considers as an almost completely fused and obliterated suturai line; 

 and he concludes that this line separates parietal and supratemporal 

 (extrascapular) elements. But, as shown above, the position of the 

 transverse supratemporal canal definitely identifies the three bones 

 immediately posterior to the parietal as the extrascapulars. The 

 imperfect suturai line that crosses the parietal may then simply be 

 a groove indicating the position of the middle head line of pit organs. 

 In the Palaeoniscidae, according to Traquair [72, p. 31], a "system 

 of slime canals was doubtless well developed in the head''; and this 

 is doubtless true also of the Platysomidae , tor Traquair says [73], of 



