No. 3.] MUSCLES AND NERVES IN AMIA CALVA. 505 
XXXVIII), crossing under the front end of the hypophysis 
immediately internal to the rectus externus and immediately 
behind the transverse ‘“‘ Wulst”’ of cartilage that marks the front 
end of the eye-muscle canal. From the vein a median branch 
is sent backward and upward into the hypophysis. Whether this 
branch communicates directly with the venous sinus along the 
base and sides of the saccus vasculosus, or passes through the 
hypophysis to supply that organ, could not be definitely decided. 
Probably the former. The hypophysis and saccus are thus in 
all probability both glands secreting, from venous blood, a fluid 
destined to fill and supply the central cavities of the brain. 
In small larvae the hypophysial fenestra is covered externally 
by the parasphenoid as in the adult, and the hypophysis lies 
directly upon that bone. The saccus vasculosus lies directly 
upon the inner surface of the base of the skull, and the trans- 
verse ridge on that base, which, in the adult, forms the posterior 
limit of the eye-muscle canal, does not exist. The processes 
of the petrosals that form the roof of the canal have also not 
yet been formed, and the hind end of the saccus vasculosus is 
separated from the base of the brain by membrane only. The 
eye-muscle canal of the adult, therefore, does not exist in 
embryos or young larvae. It is, however, represented by the 
space in which the vein vo traverses the median line of the 
skull, and by the space along the sides of the hypophysis and 
saccus in which lie, on each side, the vein vo and the rectus 
externus. 
In larvae 50 mm. in length the saccus begins to present a 
glandular appearance and the processes of the petrosals, repre- 
sented by cartilages, are well developed; the hind end of the 
saccus being separated from the brain by their united edges. 
The space enclosed by these processes, the future eye-muscle 
canal, is much larger than the saccus, and the space around 
that organ is filled with loose tissue such as that described by 
Waldschmidt in Polypterus and shown by Bickford in Cala- 
moichthys. No trace or indication whatever of a transverse 
lymph sinus in this space could be found. The eye-muscle 
canal in all probability does not, therefore, as Sagemehl was 
led to conclude, owe its origin to such a sinus. It is a space 
