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The writer (1908) described in Amphiunia two muscles having 

 their insertion upon the antorbital cartilage and innervated by a twig 

 of the 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 antor- 

 bital 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 respectively, 

 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 orbito-sphenoid 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 maxilla) and running anteriorly is inserted on the ventro- 

 lateral border of the antorbital cartilage. As in Amphiuma its action 

 is to pull the cartilage 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 somewhat 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 



