5-4 The Cephalic Veins and Sinuses of Reptiles 
may be innervated either wholly by the vagus, or partly by the vagus 
and partly by the glossopharyngeus. In Necturus all of the levator 
muscles are supplied with nerves which arise directly from the ganghon 
vagi (Fischer, 54). 
These branchial muscles of the Urodela thus bear a striking resem- 
blanee to the constrictor muscle, both in innervation and attachment. 
Moreover, the constrictor muscle also plays the part of a branchial muscle 
in certain forms. It is, therefore, not improbable that the constrictor 
muscle of the Sauria is descended from one of the mm. levatores arcuum, 
or a muscle with a similar function, belonging to amphibian ancestors. 
b. THE MuscuLus Prorrusor OCULI. 
I have been unable to find a description of this muscle in the litera- 
ture dealing with the myology of the Sauria. Its general relations have 
been recently figured by Watkinson, 06 (Figs. 12, 13, 14, Plate XII), 
in a paper on the cranial nerves of Varanus bivittatus, but the muscle is 
mistaken for the m. depressor palpebre inferioris of Weber, 77.’ 
The m. protrusor oculi of Lacerta agilis (1. p. 0., Figs. 4 and 5, Plate 
I) is closely related both to the sinus orbitalis and to the anterior part 
of the vena jugularis interna. The venter of the muscle is a triangular 
body which arises by a dorsal angle from the cranial wall anterior to the 
foramen trigemini. Its fibers spring from the posterior part of the tenia 
parietalis media, a cartilaginous rod (7. p. m., Fig. 4, Plate I), which 
reinforces the lateral wall of the cranium above the proximal portion of 
7The m. depressor palpebre inferioris was first described by Fischer, 52, 
under the name adductor maxille inferioris. The muscle was considered a 
homologue of a palatine muscle of the snake and the m. palpebralis which 
Bojanus, 19-21, described in the turtle. The actual relations and function 
of the muscle were first recognized by Stannius, 56, p. 170, who says: “ Das 
untere Augenlid wird durch eine flache, den Boden der Augenhohle bildende 
Muskelausbreitung abwarts gezogen.” In 77 the muscle was more fully 
described by Weber, who gave it the name m. depressor palpebre inferioris. 
His description, which is based on Lacerta, is as follows: 
“Der m. depressor palpebre inferioris nimmt seinen Ursprung von dem 
unteren Rande des Septum interorbitale und zwar in der ganzen Breite 
desselben; oder genauer gesagt, von dem hinteren, unteren Winkel der 
Nasenwand, dem Palatinum, dem Praesphenoid, weiter von dem Pterygoid 
und dem unteren Rande der Fascie, welche sich zwischen der Augenhohle 
und den Kaumuskeln ausdehnt. Lateralwarts schiebt sich der Muskel in 
der ganzen Breite der Augenhédhle zwischen dem bulbus und den Grund der 
Augenhohle. Er setzt sich an dem unteren Rand des Tarsus, zum Theil auch 
an das Bindegewebe, welches diesem aufliegt, an.” 
