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IOWA ACADEMY OP SCIENCE 
pterygoid branch of the ramus mandibularis trigemini. Two muscles 
similarly situated and innervated occur in Siren. In both cases they are 
evidently derivatives of the anterior part of the pterygoid muscle. In 
Amphiuma the action of these two muscles, as interpreted by the writer, 
is such that the movements of the antorbital cartilage are directly related 
to the position of the eyeball. One of the muscles raises the antorbital 
cartilage and brings the tip of the latter into contact with the eyeball, 
thus protruding the eye. The other muscle lowers and draws posteriorly 
the antorbital cartilage allowing the eyeball to sink in. These two muscles 
in Amphiuma the writer termed levator bulbi and retractor bulbi respec- 
tively, although neither one is directly connected with the, eyeball. In 
Siren a close relation of the antorbital cartilage to the position of the 
eyeball is not so apparent. But it is clear that the movements of the 
cartilage are directly related to the opening and closing of the postnaris. 
The antorbital cartilage extends laterally from its attachment to the 
orbitosphenoid around the posterior border of the postnaris, then curves 
anteriorly along the lateral border of the opening. One muscle, that 
corresponds to the retractor bulbi of Amphiuma, has its origin on the 
orbito-sphenoid bone (in Amphiuma on the pterygoid cartilage and max- 
illa) and running anteriorly is inserted on the ventro-lateral border of 
the antorbital cartilage. As in Amphiuma its action is to pull the carti- 
lage posteriorly and ventrally. This movement from the relation of the 
cartilage to the lateral valvular fold of the postnaris will open the latter. 
The other muscle, which has its origin on the side of the orbito-sphenoid 
(as in Amphiuma) and its insertion on the posterior dorsal part of the 
antorbital cartilage, by its contraction raises the latter and pulls it some- 
what anteriorly, thus closing the postnaris. Fischer (1864) and later 
Wilder (1891) noticed the relation of the posterior of these two muscles 
to the lateral valvular fold of the postnaris, but neither detected the 
other muscle, nor, apparently, determined the insertion of the retractor 
muscle on the antorbital cartilage. As this cartilage in Siren has no 
close relation to the eyeball it is hardly appropriate to designate its 
muscles as bulbar muscles. They are here termed retractor and levator 
antorbitalis muscles, as they should have been designated in Amphiuma. 
Their origin, insertion and innervation in Siren point to their complete 
homology with the muscles in Amphiuma termed retractor and levator 
bulbi. They evidently do not correspond to any of the muscles described 
by Bruner (1901) in the Urodela and Anura, which are concerned with 
the regulation of the size of the opening of the prenaris. 
Wilder states that in Siren a “ ramus palatinus posterior” of the facial 
nerve innervates a few of the anterior fibers of the cerato-hyoideus exter- 
