6o ALUS. [Vol. XVIII. 



already been stated by me in one of my earlier works (No. 7), in 

 which the so-called ethmoids of certain other fishes were com- 

 pared with that of Aiiiia. In that work I stated my opinion that 

 the two bones in Esox called by Huxley " Bones 2 " were probably 

 the homologues of the ethmoids of Amia and Saliiio. Since then 

 I find that Gegenbatir (No. 29, p. 9) has described a bone in 

 Alepocephahts as the ethmoidale median, and said of it that it 

 is an "unpaares Knochenstiick — bei Esox paarig — ." The bones 

 of Esox here referred to must be bones 2 of Huxley, which bones 

 were thus considered by Gegenbaur as ethmoids. The median 

 ethmoid of Alepocephalns is said to overlap externally (lateral 

 umgreifen) the f rentals of that fish, and to be the homologue of 

 the bone called by Parker in Sahno the supraethmoid. It has 

 a ventro-lateral process resembling strongly the corresponding 

 process in Scomber, the process giving articulation either to the 

 palatine, alone, or to both that bone and the maxillary. The 

 bone is said to be one of the "secondaren Knochen" (No. 29, p. 

 29), as is also the palatine, but both of these bones are said to 

 differ from the other secondary bones of the fish in not being 

 separated from the underlying cartilage by perichondrium. 

 Whether this ethmoid bone of Alepocephalns is the homologue of 

 the similarly named bone in Amia, or of that of Scomber, it is 

 impossible to determine from the descriptions. 



In Gadus cegleiimis (No. 12), the ethmoid is said by Brooks to 

 be overlapped externally by the frontals, and in this as .well as in its 

 relations to the skull it agrees closely with the ethmoid of Scomber. 

 The ossification has, however, extended forward and downward, 

 and includes the cartilaginous beak of Scomber. It gives attach- 

 ment, on each side, as in Scomber, to a strong ligament that has its 

 insertion on the maxillary ; and it gives articulation, on its anterior 

 edge, to a rostrale, called by Brooks the pre-ethmoid cartilage. 



The Rostrale {R) of Scomber is a small, flat, detached piece 

 of cartilage, connected by fibrous tissue with the anterior end of 

 the skull. It is roughly square, or slightly hexagonal, in general 

 outline, with a prominent process or shank at the middle of its 

 lower edge. At the middle of its upper edge there is a sharp in- 

 dentation, from which shallow grooves extend downward, a short 

 distance, on both the outer and the inner surfaces of the piece. 



