On the Vomer in Man and the Mammalia. 97 



bones. But this surface ceases abruptly in front, and only 

 the lamina bounding the groove for the cartilage is prolonged 

 on the intermaxillary part of the palate (fig. 3). In the adult 

 state both the scooped projection lying on the intermaxillaries, 

 and the remains of the surface for articulation with the supe- 

 rior maxillaries, can be seen, when the vomer still admits of 

 being accurately disarticulated. But this is not often, as it 

 soon becomes anchylosed with the neighbouring bones ; and 

 even when this has not happened, it requires that portions of 

 the other bones be sacrificed for the sake of removing it en- 

 tire. As the face elongates, the upper part of the vomer 

 undergoes much alteration ; not only is there a considerable 

 development of lamina in the mesial plane beneath the groove, 

 but usually the laminae bounding the groove deviate from the 

 mesial line, and one of them becomes more developed than the 

 other, and is more extensively anchylosed with the central 

 plate of the ethmoid, which, growing downwards, replaces the 

 cartilage between them. In consequence of these changes 

 taking place at a comparatively early period, the specimens 

 which are sold with disarticulated skulls, and from which the 

 descriptions in text-books are drawn up, are seldom complete, 

 and have most frequently more or less of the central plate of 

 the ethmoid adherent to them. Thus the vomer is described 

 as exhibiting at its upper and back part a cul-de-sac for the 

 rostrum. Such a cul-de-sac is often seen, but the central plate 

 of the ethmoid invariably enters into its formation, for it is 

 only the ethmoid, and never the vomer in the slightest degree, 

 which replaces the cartilaginous septum. 



Explanation of Plate V. 



Fig. L The vomer and lateral masses of the ethmoid of a iamb, seen from 

 below, a, The inferior margin of the vomer, rough posteriorly, for articulation 

 with the maxillaries, and smooth in front, where it comes in contact with the 

 intermaxillaries; b b, the grooves which complete the nasal foramina? of the 

 palate bones. The spaces between the grooves and the margins of the vomer 

 represent the ethmo-vomerine laminae, and on the outer aspects of the grooves 

 are the small orbital surfaces of the ethmoid. 



Fig. 2. The vomer, ethmoid, sphenoidal spongy bones, and left palate and 

 maxillary bones, from the skull of an infant ; seen from behind (slightly en- 

 larged), a, Orbital plate of the ethmoid ; &, posterior extremity of the vomer ; 

 c, sphenoidal process of the palate bone ; d, orbital surface of the palate 

 bone, and immediately above it is the orbital portion of the sphenoidal spongy 

 VOL. II. N 



