92 Proceedings of the Royal Physical Society. 
vomerine segment of the skull, although it is one on which 
the statements to be made have an important bearing ; I shall 
content myself with exhibiting the relations of this bone in 
different mammalia, and, founding upon these and on deve- 
lopment, shall show how the vomer in man corresponds in its 
relations to those of other animals, and what is the nature of 
the sphenoidal spongy bones. 
Last autumn, while disarticulating the skull of a lamb, it 
came prominently under my notice that the central plate of 
the sphenoid bone adhered without marks of separation to the 
presphenoid, while the lateral masses of the ethmoid and the 
vomer formed one other single piece. On further examination 
I found that in mammalian skulls the formation of one piece 
by the vomer and lateral masses of the ethmoid was the gene- 
ral rule, and their separation a rare exception. This is a cir- 
cumstance so easily seen that one would think it could hardly 
escape the notice of any one in the habit of disarticulating 
mammalian skulls, yet I can find no description of it by 
authorities on human and comparative anatomy. It is, how- 
ever, as we shall see, the most important of all the connections 
of the vomer, and throws some valuable light on human ana- 
tomy. With respect to the other articulations of the vomer, 
we shall see, that that with the central plate of the ethmoid is 
by no means a primary one, and that the most constant of those 
of its inferior margin is that with the intermaxillary bones. 
In the Tuminantia it is a well-developed elongated bone. 
Let us take that of the lamb as an example. It consists 
principally of two laminae united inferiorly so as to form a 
groove ; deepest posteriorly where the laminse are most de- 
veloped, and shallowing away to a scooped extremity in front. 
In this groove lies the cartilaginous septum of the nose, which 
is continuous behind with the presphenoid bone. The pos- 
terior extremity of the vomer is bifid and slightly dilated, as 
it is in man, and in front of the dilatation the lines of mar- 
gin begin to approach, and seem as if they would pass directly 
forwards ; but they are almost immediately lost as fissures in 
two lateral expansions, which, springing from the vomerine 
laminse, pass outwards to the outer and back part of the 
ethmoid, and are continuous with the principal arches of the 
