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 laminse 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. 1. The vomer and lateral masses of the ethmoid of a lamb, 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; & 6, the grooves which complete the nasal foraminae of the 
palate bones. The spaces between the grooves and the margins of the vomer 
represent the ethmo-vomerine laminee, 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; 6, 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 
