. CRANIAL NERVES OF CAECILIANS 507 



border of the external sheath of the tentacle. The first is in- 

 nervated by the abducens nerve, the second by the oculomotorius. 

 The second muscle will be designated as the retractor muscle 

 of the tentacular sheath (rts.). Six muscles, all nearly vestigial, 

 are attached to the eyeball, in two groups. Originating from the 

 sheath of the retractor tentaculi at its lateral ventral border is a 

 muscle that has its insertion on the lateral posterior border of 

 the eyeball, and evidently represents a rectus lateralis (rext.). 

 A second one originating near the preceding, but from the sheath 

 of the retractor of the tentacular sheath, is inserted on the ven- 

 tral border of the eyeball and constitutes a rectus ventralis 

 (rinf.). Inserted on the dorsal wall of the eyeball is a muscle 

 that originates by a slender tendon from the medial border of the 

 sheath of the retractor of the tentacular sheath, a rectus dorsalis 

 (rs.). As in Dermophis, so in Geotrypetes, a delicate muscle slip 

 follows the optic nerve from the retractor tentaculi to the eye- 

 ball, probably a retractor bulbi (rth.). Two oblique muscles, as 

 in Dermophis, arise from the dorsal and ventral walls of the 

 tentacular canal and are inserted on the eyeball just anterior to . 

 the insertions of the dorsal and ventral rectus muscles. The 

 faulty differentiation of nerve fibers in the specimen studied 

 does not permit tracing the innervation of the vestigial ocular 

 muscles. The position and innervation of the retractor of the 

 tentacular sheath indicate that it represents a rectus medialis. 

 This relation of the oculomotorius to the retractor muscle of 

 the tentacular sheath clears up statements made by Waldschmidt 

 that in Siphonops the compressor muscle of the orbital gland is 

 innervated by the oculomotorius. In Geotrypetes, as the third 

 nerve passes out through the optic foramen, it comes into close 

 relations with the compressor muscle, and in an ordinary dissec- 

 tion might seem to end in the latter muscle (fig. 18). Marcus' 

 statement that the third nerve innervated the levator bulbi 

 (compressor) is not so easily explained, but is plainly an error. 

 Waldschmidt figures an anastomosis between the ramus maxil- 

 laris V and the oculomotorius in Siphonops. In Geotrypetes 

 the small branch of the ramus mandibularis V (^md. 1) which in- 

 nervates the compressor muscle of the orbital glands, runs, as in 



