No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 519 
The rectus superior, rectus inferior, and rectus internus are 
all innervated by the nervus oculomotorius (ocm). This nerve 
pierces the lining membrane of the cranial cavity opposite and 
above the optic chiasma, and enters the orbit through the 
upper end of the large orbital opening of the eye-muscle canal. 
Lying dorsal to all the recti muscles at their origin, it separates 
into a superior and an inferior portion. The superior portion 
(ocms), dividing dichotomously, supplies the rectus superior 
alone, one branch going to the upper and the other to the 
under surface of the muscle, each branch dividing dichotomously 
before reaching the muscle. The inferior, or main portion (ocmz?) 
of the nerve runs forward and downward between the rectus 
superior and the rectus externus, and behind or external to the 
rectus inferior. It then turns forward below the rectus inferior 
and rectus internus, and sends two branches, arising close 
together, if not from a common root, one to the upper and the 
other to the under surface of the former muscle, and two 
branches, arising some distance apart, each of them double, to 
the latter. The nerve then separates into two parts, which 
again divide dichotomously and enter and end in the obliquus 
inferior, entering the muscle on its under and upper sur- 
faces. 
The inferior and internal recti were, in the specimen used 
for illustration, connected about midway of their length by two 
or three muscle strands, which arose distally in each muscle 
—that is, toward their insertions— and formed a festoon con- 
necting them. In another specimen the two muscles arose as 
a single muscle, which soon separated into two parts. 
6. Review and Comparison of the Muscles and Nerves of the Eye. 
In Amia the obliquus superior is innervated by the troch- 
learis, the rectus externus by the abducens, the rectus superior 
by the superior branch of the oculomotorius, and the rectus 
inferior, rectus internus, and obliquus inferior, in the order 
named, by the inferior branch of the oculomotorius. The 
inferior branch of the oculomotorius runs forward and down- 
ward behind and below the rectus superior, above and in front 
