BLOOD-VASCULAR SYSTEM OF THE LORICATI 61 
of the nasal sac. They penetrate the base of the filaments 
with branches of the olfactory nerve, and running through the 
inner connective tissue layer send off branches into the secon- 
dary or branching filaments. The main orbito-nasal trunk 
after passing behind the nasal sac with the corresponding vein 
and the olfactory nerve divides into a cephalic and a ventral 
branch. The smaller cephalic branch, crossing behind the or- 
bito-nasal vein, proceeds above it, and becomes the mawzlla 
Gren (eis lands li, nes? 1.17 and 13; Max:A. 7.) Ehis 
artery in turn also breaks up into 2 vessels; a dorsal one, which 
penetrates the premaxilla; and a ventral one, which runs along 
the posterior surface of the premaxilla. The larger ventral 
branch is the fostertor maxilla artery (Pls. I and III, figs. 1, 17 
and 18; Max.A.,)); at the ventral edge of the nasal sac it sends 
a branch inward to the palatine arch; and directly below this 
branch at least 2 ventral nasal sac artertes (PI. Ill, fig. 17; 
N.S.A.,,)) are given off dorsad, which supply the ventral fila- 
ments in a like manner to dorsal nasal sac arteries. Then an- 
astomosing with the much smaller facialis-maxillaris artery it 
runs along and breaks upon the outer surface of the adductor 
mandibulz muscle, immediately behind the maxilla. 
(c) Summary of the Carotids. — Parker has well said (60, P. 
653), that: ‘*The application of the name ‘carotid’ to the ce- 
phalic arteries of fishes must of course be taken to imply nothing 
more than a general correspondence with the similarly named 
vessels in the higher Vertebrata.” For example, his anterior 
carotid (internal carotid) in M/uste/us (60, fig. 6), and the similar 
artery in Hydrolagus, Chimera (PI. III, fig. 26; I.Car.A.), are 
almost analogous to the ophthalmic artery of Ophzodon (PYvis 
figs. 1and5 ; Oph.A) provided that it anastomosed with the orbito- 
nasal artery with which it comes in such close contact. In the 
same connection, Parker proposes to substitute the names ante- 
rior and posterior carotids for the internal and external carot- 
ids. This substitution may seem advisable in the Selachians, 
where the carotids at first occupy a distinctly anterior and pos- 
terior position ; but in the case of the Teleosts that I have exam- 
ined the vessel which has been designated as the internal car- 
otid has a distinctly profundus course, and the external carotid 
