Nos. IAND2.] ANATOMY OF SCOMBER SCOMBER. 65 



In Gad us cvglcfiiius (No. 12) the maxillary and premaxillary 

 much resemble the corresponding bones in Scomber. They both 

 articulate with and are bound to a median ro.strale, and this latter 

 element is movable upon the anterior end of the ethmoid. The 

 maxillary of Gadiis, however, is said to articulate directly and 

 independently with the skull in a cartilaginous groove between the 

 ethmoid and vomer, and the bone is, accordingly, much less inti- 

 mately connected with the premaxillary than in Scomber. There 

 is also a strong ligament, not found in Scomber, which arises from 

 the apex of the ascending process of the premaxillary, on each 

 side of the head, and, crossing the median line dorsal to the eth- 

 moid, is inserted on the palatine bone of the opposite side. W^hat 

 seem to be the representatives of the little articular surfaces that 

 I have described on the two bones in Scomber are, several of them, 

 said to be simply the points of attachment of certain connecting 

 ligaments. Otherwise there is a strong resemblance in the arrange- 

 ment of the parts concerned in the two fishes. 



The ascending process of the premaxillary I consider, as fully 

 set forth in one of my earlier works (No. 7), as the probable 

 homologue of one half of the ethmoid bone of Aiuia fused with 

 the premaxillary of that fish. To the several references there 

 made to other fishes, in support of this conclusion, Alepocephalus 

 may here be added ; for in that fish the ethmoid is said by Gegen- 

 baur (No. 29) to be of dermal origin and to overlap externally the 

 frontal, and the premaxillary is said to have no ascending process. 



No Septomaxillary, as a separate bone, is found in Scomber. 

 There is, however, as already stated, a process of the chondro- 

 cranium which fulfills the function of the septomaxillary process 

 described by Sagemehl in cyprinoids. This process, in the cyprin- 

 oids, is said to articulate directly with the palatine, and indirectly, 

 by means of a "Zwischenknorpel," with the maxillary. In Scom- 

 ber it articulates with the palatine alone ; but the hind edge of the 

 dorsal articular head of the maxillary hooks around the ventro- 

 lateral process of the ethmoid, and hence to a certain extent articu- 

 lates with it. The process, in Scomber, also presents practically 

 the same relations to the palatine and maxillary that the sexto- 

 maxillary region of the skull of Amia does to those same bones. 

 That part of the ethmoid of Scomber that occupies the base of this 



