1^2 ALUS. [Vol. XVIII. 



rently wholly wanting in Scomber; but there is nothing to defi- 

 nitely indicate whether it is the ethmoidal organs and bone that 

 have disappeared, or the antorbital ones. The other two organs 

 of Amia, whichever two it may be, are certainly represented in 

 the first organ of the supraorbital canal of Scomber, that organ 

 being innervated by a branch that arises from the fused buccalis 

 facialis and maxillaris superior trigemini, as will be fully described 

 in describing those nerves. In Gadiis this supraorbital organ of 

 Scomber is apparently represented in a pit organ said by Cole to 

 lie opposite the anterior extremity of sense organ i supraorbital. 

 The course of the nerve that innervates this pit organ in Gadus 

 seems to indicate, as I have already had occasion to state (No. 8, 

 p. 366), that the single organ in Gadus represents the two canal 

 organs in the ethmoid of Amia. The shape of that part of the 

 nasal bone of Scomber that lodges the buccalis supraorbital organ, 

 its relation to the other bones of the region, and the presence of 

 an ascending process to the premaxillary, all indicate, on the con- 

 trary, that the anterior part of the nasal of Scomber is the homo- 

 logue of the antorbital bone of Amia, the organ in the nasal bone 

 of Scomber being, in that case, the homologue of the antorbital 

 organs of Amia. 



In Gadus the organs innervated by the facialis are separated by 

 their innervation, as given by Cole, into four groups, as they are 

 also in Amia and Scomber. Organ No. i forms the first one of 

 these four. groups, organs 2-6 the second, organs 7-10 the third, 

 and organ 11 the fourth. Whether the organs assigned to the 

 third and fourth of these groups, in these three fishes, do not, in 

 reality, form but a single group, artificially separated into two 

 groups because of the name oticus given to the branches that 

 innervate certain of them, is open to question. The second and 

 third groups, in all three fishes, seem, on the contrary, to be so 

 definitely separated from each other by their innervation, and in 

 Amia also by the manner in which they are enclosed in their can- 

 als, that there may be here an anatomical fact of some importance. 

 They may represent, in teleosts, the two separate, ventral and dor- 

 sal, infraorbital lines of Chimccra. 



The possibility, or even probability, of system 14 infraorbital 

 of Scomber being a double and not a simple system will be dis- 

 cussed in describing the supratemporal commissure. 



