296 
DE. CLELAND ON THE EELATIONS 
are composed of large turbinations imbedded in a dense mass of small leaflets, and both 
leaflets and turbinations lie at right angles to the cribriform plate, in Man there are no 
such leaflets and only two stunted turbinated processes, which, instead of descending to 
fill the nasal cavity, immediately curve backwards so as to occupy as little room as 
possible. And not only is the ethmoid so rudimentary, but by the curvature of the 
cranial arch, the vomer is moved away from it ; its anterior extremity sloping rapidly to 
a lower level, and its posterior being pushed backwards under the sphenoid. Of this 
latter fact we may be convinced by comparing the position of the human vomer with 
that of the same bone in the Cat. The Cat has got sphenoidal sinuses as well as Man, 
but they are floored-in entirely by projections downwards from the wings of IifGRASSiAS ; 
and the part of the vomer which is continued into the ethmovomerine laminae lies, not 
underneath the sinuses, but underneath the ethmoid, immediately in front of the sinuses. 
Moreover, it is very important to keep in mind that the margin of the ethmoid which 
is placed posteriorly in the human skull is that which is. morphologically inferior, and 
which corresponds to that to which the ethmovomerine lamina is habitually attached, 
and to which therefore it behoved that the human vomer should be connected. This 
will be best illustrated by using the vomer and ethmoid of the Sheep, Dog, or Eabbit 
for comparison. It will then be easily understood, on referring to Plate IV. fig. 5, how 
there comes to be a space left between the ethmoid and vomer, to bridge over which the 
large and peculiar development of ethmovomerine laminae as sphenoidal spongy bones 
becomes necessary (fig. 5). 
Varieties presented hy the Vomer and Intermaxillaries in different Classes of Mammalia. 
In the Quadrumana the vomer comes to a point anteriorly, which is so directed that 
the vomerine groove is continuous, as in other animals, with the upper surface of the 
intermaxillaries; but it never comes further forwards than just to touch them, and 
sometimes falls short of them by a slight interval. This is owing to a want of develop- 
ment of the mesial-palatine processes of the intermaxillaries, these bones having in the 
Quadrumana begun to suflier that atrophy which they undergo in the human subject; 
and as theh bulk is occupied almost entirely by the sockets of the large incisor teeth, 
while, on the other hand, the cartilages of the nose are httle developed, there is no 
appearance of the crista incisiva found in Man. The ethmoid and vomer are continuous, 
according to the normal plan, save only in the Orang ; and we may therefore confine our 
attention to the arrangement in it and in the Chimpanzee. In two skulls of Chimpan- 
zees in the University Museum, the posterior part of the vomer arches out on each side 
into a lamina which passes up in front of the sphenoid to be continuous with the orbital 
plate of the ethmoid, as in other Quadrumana ; but both are skulls of animals of such an 
age that they present anchylosis of many sutures. In the Orang, however, there are 
certainly separate sphenoidal spongy bones. The examination of three young Orang 
skulls gives the following results. In the largest skull, the sphenoidal spongy bone 
is quite distinct on the right side, both from the orbital plate of the ethmoid and 
