ANATOMY OF THE HORSE. 
*187 
divided by a broad perpendicular plate, which extends upwards 
to unite with the nasal spine; (the partition between the fron¬ 
tal sinuses;) below, it is received into the groove of the vomer; 
while in front it sustains the cartilaginous septum of the nose, 
the septum nasi; altogether completing the division of the nasal 
cavity into two chambers : the ethmoidal plate itself is com¬ 
posed of two thin laminae which in old subjects become conso¬ 
lidated into one. Posteriorly, on either side, the body presents 
the optic hiatus, transversely oval, leading to the optic foramen: 
the posterior surface is oval to,form a junction with the sphe¬ 
noid bone. Arising from the upper and fore part of the body is 
a pyramidal eminence somewhat curved, called the crista galli : 
it sustains in front the perpendicular plate, the falciform process 
of the dura mater behind, while from its sides extend the cribri¬ 
form plates—two ovoid, thin, brittle lamellae, which are received 
between the frontal orbital plates and the floors of the frontal 
sinuses, pierced by numerous small holes for the transmission of 
the filaments of the olfactory nerves, and whose concave cere¬ 
bral surfaces are denominated the ethmoidal fossae and are 
occupied by the olfactory sinuses. To the outer side of either 
fossa opens the internal orbital foramen, from which a fissure 
runs upward to the part of the cribriform plate connected with 
the principal cornu among the ethmoidal cells.— The Ethmoi¬ 
dal Cells, the voluminous structure protruding from the front 
of the cribriform plates, consists of a great many thin, brittle, 
porous osseous plates, curved or rather convoluted so as to form 
numerous narrow, elongated, cornuform sinuses, rendered sepa¬ 
rate and distinct from one another by intervening longitudinal 
grooves, with which from above they all in common have com¬ 
munication. These canals proceed, converging a little as they 
advance, to terminate underneath the superior turbinated bone, 
at the back of the nasal fossa, within a space communicating 
with the middle meatus. The anteriormost cornu or cell is con¬ 
spicuously long and capacious: the rest increase in dimensions 
according to their proximity to this large one. Issuing from the 
front of the cells is a broad, thin, funnel-like process, which 
unites with the superior turbinated bone and forms a sharp pro¬ 
minent crest, serving as an imperfect septum between the 
frontal and maxillary sinuses. 
The Lateral Portions, alse or wing's, display more convexity 
than concavity superiorly, the reverse inferiorly: they originate 
from the supero-lateral parts of the body; consist of thin, flex¬ 
ible plates ; spread outward and upward, contributing to the 
posterior and inward parts of the orbits ; and terminate in semi¬ 
circular borders, sloped off behind, which, posteriorly, lie upon 
