BLOOD-VASCULAR SYSTEM OF THE LORICATI 53 
ciliary nerve and internal jugular vein it passes cephalad out 
of the skull through the large olfactory-optic foramen, then 
curving laterad in company with the ramus ciliaris longus and 
the iris vein it crosses under the orbito-nasal vein and the trun- 
cus supra-orbitalis, passing between the superior and external 
rectus muscles, gives off a branch to the latter (Pl. II, figs. 13 
and 15; Ex.R.A.). Then running laterad across the posterior 
dorsal surface of the eyeball it penetrates the sclerotic coat in 
its median line, and continuing laterad in the silver layer of the 
choroid until the iris is reached, where, with the ramus ciliaris 
longus, it bifurcates into 2 ventral vessels, which supply at 
least the dorsal half of the iris. The normal arrangement of 
the iris vessels is first the iris vein, then the ramus ciliaris lon- 
gus, and finally the iris artery, but in several cases I have 
observed the artery curving cephalad and passing between the 
nerve and the vein. 
The second vessel is given off a little below the sclerotic-iris 
artery ; and after making a rather sharp caudal curve terminates 
in the levator arcus palatini muscle. The next vessel is the 
Sacialis-maxillaris artery (Pl. I, fig. 1; F.Max.A.) which arises 
cephalad from the external carotid in the region of the orbit, 
and passes obliquely over the external jugular vein and the ramus 
mandibularis or the ramus maxillaris inferior, where it gives off 
a large ventral branch, the faczal artery (Pl. I, fig. 1; F.A.), 
for the adductor mandibule muscles. This branch runs along 
the lateral surface of the deeper portion of the adductor mandi- 
bulz, giving off numerous branches to the adductor muscles, 
but does not follow the nerve to the mandible. The main por- 
tion of the facialis-maxillaris artery proceeds along the floor of 
the orbit in the adductor arcus palatini muscle, to which it gives 
off numerous branches, and when the level of the nasal sac is 
reached it receives a much larger artery from the orbzto-nasal 
artery (Pls. Y and Wij-figs. 1 andi17; O.N.A.), which isa 
branch of the internal carotid artery." This combined vessel 
continues in a cephalic direction, supplying the region directly 
1 McKenzie (52, p. 427) mentions the crossing of the branches of the ex- 
ternal and internal carotids in the neighborhood of the nasal sac, in Amezurus 
but nowhere have I met with the statement of their union. 
