536 ALLIS. [Vou. XII. 
and tissues of the snout. In his later publication (No. 29, p. 
75), which seems to give the distribution of the nerves in sharks 
in general rather than in Laemargus in particular, Ewart 
describes a ciliary ganglion lying at the junction of the pro- 
fundus and oculomotorius fibres. From this ganglion the 
ciliares brevi arise, the ciliares longi arising from the main r. 
ophthalmicus profundus, as in Laemargus in particular. The 
profundus is here said to pass under the rectus internus instead 
of over it, between it and the obliquus superior, as in the pre- 
liminary publication. This earlier statement is, therefore, 
probably an error. It apparently never fuses with the r. 
ophthalmicus superficialis trigemini, and Ewart says it has 
a distribution similar to that in Raja and in Amia. No 
reference is given, in this particular instance, indicating his 
authority for the statement regarding Amia. It is, however, 
probably based on my earlier work (No. 3), as definite reference 
is made to that work in describing the nerve in Raja (No. 32, 
p. 90). The nerve referred to in Amia is, therefore, probably 
the portio ophthalmici profundi, and not the ramus ophthalmicus 
profundus. 
In Scyllium, Schwalbe (No. 113) says that the profundus 
perforates the rectus superior near its hind edge and then runs 
forward under the rectus internus and obliquus superior, pass- 
ing, however, in its course through the sclerotic, a fact con- 
firmed by Marshall and Spencer (No. 77) in the embryo. In 
Hexanchus it apparently has a similar course (Gegenbaur). 
In Galeus (see Cut 1) it lies above the rectus superior, running 
downward in front of that muscle, through the rectus internus, 
near its hind edge, and then forward below the rectus internus 
and obliquus superior. In Mustellus, Schwalbe gives it a 
similar course, but Tiesing (No. 123) says that it issues below 
the rectus superior and lies below that muscle, below the 
internus, and below the obliquus superior. Whatever its rela- 
tions to the muscle of the eye, it always lies behind, or external 
to, and then below, the superior branch of the oculomotorius, 
and above the inferior branch of that nerve; that is, it crosses 
the upper surface of the oculomotorius distal to its superior 
branch, and then runs forward always under the trochlearis. 
