— 17 - 



endosteal bone, may have existed in earlier fishes, I can not contest, butl greatly doubt it; the appar- 

 entlv dermal prefrontal described in certain fishes belonging, in my opinion. to the frontal or nasal 

 series and fusing with one or the other of those bones and not with the ectethmoid. 



V M E R. 



The vomer caps the pointed anterior end of the antorbital cartilage, and has dorsal and ventral 

 limbs, one of which forms part of the dorsal, and the other part of the ventral surface of the anterior 

 end of the skull. The anterior edge of the bone has the shape of a broad V, the point of the V directed 

 forward in the middle line; and on the ventral surface of this edge of the bone there is a narrow 

 raised surface the anterior portion of which is garnished with small villiform teeth, the band of teeth 

 passing uninterruptedly from one side of the head to the other. This part of the vomer forms the 

 head of the bone. Posterior to this head, the ventral liinb, or body of the bone projects backward 

 along the ventral surface of the skull as a thin plate which tapers rapidly to a sharp point. In its 

 anterior portion, the body of the bone lies against the ventral surface of the antorbital cartilage, while 

 posteriorly it flts into a depressed region on the ventral surface of the parasphenoid. The bone has 

 no pronounced lateral processes, such as are found in Scomber, but in the angle between the head and 

 the body of the bone, on either side, there is a slight process which projects toward, and in large 

 specimens may even come in contact with, the anterior end of the ventral plate of the corresponding 

 ectethmoid. This little process has already been referred to, when describing the ectethmoid, this 

 latter bone and the process of the vomer both growing toward and giving support to the anterior 

 palatine articular process of the ethmoid cartilage. Immediately anterior or antero-mesial to this 

 slightly developed lateral process of the vomer, on the ventral surface of the bone, and slightly 

 posterior to the raised portion that bears the villiform teeth, there is a large but shallow depression 

 which gives origin to a strong ligament, the vomero-palatine ligament, which has its insertion on the 

 mesial surface of the palatine. 



On the dorsal Limb of the vomer there is a median ridge which forms an anterior Prolongation of 

 the median ridge on the mesethmoid. A median interspace of cartilage intervenes between the two bones 

 and extends forward a variable distance in a median slit in the hind edge of the dorsal limb of the 

 vomer, this slit separating this limb of the vomer into two parts which may be called the right and left 

 ascending processes of the bone. Near the hind end of the interspace of cartilage, and immediately 

 in front of the mesethmoid, there is a marked angle in the mid-dorsal line of the cartilage, this angle 

 King not far from the middle of the entire internasal ridge. On either side of the median ridge, there 

 is, on the dorsal surface of each ascending process of the vomer, a depressed region, and in the line of 

 the bottom of this depression, near the anterior edge of the bone, there is a slight eminence which is 

 found much more developed in the Triglidae. With the lateral surface of this eminence, and in the 

 depressed region posterior to it, the postero-ventral portion of the ascending process of the maxillary 

 articulates, as will be later described. 



The ascending processes of the vomer are each in sutural contact, posteriorly, with the anterior 

 end of the perichondrial portion of the mesethmoid; and this posterior portion of these processes 

 has, in the adult, strikingly the same appearance as the adjacent perichondrial portions of the three 

 ethmoid bones. The vomer can, however, be removed from the skull, in slightly macerated specimens, 

 without apparently injuring, in the least, the underlying cartilage. Whether, because of this, the 

 entire bone should be considered as of purely membrane origin, or not, I can not decide ; but it would 



Zoologica. Heft 57. 3 



