No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 737 
and a dorsal ganglion. Similar roots and ganglia are found in 
Scyllium (Corning), Pristiurus (Kaestner, No. 62, p. 188), and 
reptiles (Corning), while in Acanthias (Hoffmann) there is 
simply a rudimentary ganglion which soon disappears. Van 
Wijhe did not find in Scyllium the dorsal root or ganglion 
described by Corning in this somite, and Mollier also (No. 82, 
p- 483), in reptiles, seems to have found the first ganglion 
opposite the fifth segment and not opposite the fourth. 
Amia, therefore, in its occipital region presents nothing new 
or different from what has already been described in selachians, 
teleosts, and reptiles. With Protopterus, as described by 
Pinkus, it is impossible to make any comparison, for in Protop- 
terus (No. 89, p. 325) there are, in the occipital region of the 
head, three ventral roots, and three complete spinal nerves, 
two of which are called by Pinkus the first and second hypo- 
glossi. The two posterior ventral roots are distributed to the 
“umliegende Visceralmuskulatur.” The anterior one is simply 
said to run backward along the under side of the basis cranii, 
but as it joins, in the figures, the two posterior roots, it prob- 
ably has the same distribution that they have. The two hypo- 
glossi are distributed in part to the first and second trunk 
muscle segments, in part to the tongue, and in part they join 
branches of the first three spinal nerves to form the brachial 
plexus and take part in the innervation of the fin. 
GENERAL SUMMARY. 
1. The eye-muscle canal of Amia and its tall, orbital open- 
ing present, in certain respects, striking resemblances to the 
pituitary fossa, or sella turcica, and the sphenoidal fissure of 
the human skull. The pituitary fossa, in man, is bounded 
behind by the dorsum sellae of the sphenoid bone, and in 
front by the olivary eminence of the same bone. In Amia the 
eye-muscle canal is bounded behind by the median, horizontal 
wings of the petrosals, and in front by a transverse cartilagi- 
nous bar, on the sloping, dorsal surface of which the optic 
chiasma rests. On this sloping surface, in Amia, as on the 
olivary eminence, in man, the optic nerves pass outward to 
their foramina, accompanied by the ophthalmic arteries. In the 
