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XVI. On the Belations of the Vomer, Ethmoid, and Intermaxillary Bones. 
By Clelajs'd, M.D., Demonstrator of Anatomy in the University of Edinburgh. 
Communicated by Professor Huxley, F.B.S. 
Eeceived February 28, — Bead March 21, 1861. 
Ix a paper read before the Eoyal Physical Society of Edinburgh, in March 1859*, I 
have drawn attention to the fact, not before noticed, that in Mammalia the lateral 
masses of the ethmoid always lie edge to edge with the dilated part of the vomer, and 
are usually united with it to form one bone. I have shown that in the human subject 
the sphenoidal spongy bones represent, in a disrupted and altered form, the plates by 
which in other mammals this union is effected; and these plates I have ventured to 
call the ethmovomerine laminse. 
A further inquiry into the variations of these bones and their development has not 
only confirmed my former statements, but led to other conclusions of most important 
morphological bearing. 
It will be convenient to consider, in the first place, the typical connexions of the 
vomer in the mammal. We shall then examine the peculiar modifications which the 
vomer, ethmoid, and intermaxillaries undergo in the human subject. Afterwards we 
shall re\iew in detail the varieties of their connexions in a number of mammalian 
families, and endeavour to deduce their morphological relations. Lastly, we shall glance 
at the arrangement of these bones in the other classes of Vertebrata, and draw such 
additional morphological conclusions as our observations shall seem to warrant. 
Typical Connexions of the Mammalian Vomer. 
In all young mammals the septal cartilage of the nose extends backwards to the pre- 
sphenoid bone, and the vomer embraces its inferior edge. The vomer is known to be 
developed from two centres of ossification, one on each side ; it always consists there- 
fore fundamentally of two alse ; and between these a groove runs along its whole length, 
and is occupied by the septal cartilage. 
Anteriorly it articulates generally with the mesial-palatine processes of the intermax- 
illaries. Sometimes this articulation does not take place, to wit, where the intermaxil- 
laries have either no mesial-palatine processes or very short ones ; but, when it exists, it 
is always of such a character that the vomerine groove is continued forwards by a groove 
between the intermaxillaries, while also the inferior aspect of the mesial processes of the 
intermaxillaries lies in a continuous line with the inferior edge of the vomer. 
* Edinburgli New Philosopbical Journal, October 1859. 
2 R 
MDCCCLXII. 
