546 JULIA B. PLATT. 
mandibular sense-organs, i.e. sense-organs of the primitive ventral longi- 
tudinal ridge. v././. Ventral lateral line. v.r. Ventral longitudinal ridge. 
1x, x'*. Rami post-trematici glosso-pharyngei et vagi. xg. Lateral line gan- 
glion. 1X8.0.,Xs.o. Sense-organs supplied respectively by dorsal branches of 
the glosso-pharyngeus and vagus. * Branch of ramus buccalis vi. ? Sense- 
organs on the vagus commissural line in an unusual position. 1, 2, 3, 4. 
Sense-organs supplied by buccalis vii and ophthalmicus profundus v. 
PLATE 36. 
Fie. 2.—a. Cross-section through the supra-orbital sensory ridge. 0. 
Cross-section of the primitive supra-orbital (dorso-lateral) ridge. The planes 
of sections 2, 3, 4, 5, are given in Pl. 38, fig. 1. 
Fie. 3.—Cross-section through the facial part of the primitive epibranchial 
ridge. 
Fie. 4.—Cross-section through the primitive epibranchial ridge, as it gives 
rise to the lateral ganglion. 
Fic. 5.—Horizontal section through the lateral line ridge of Pl. 38, fig. 1. 
Fics. 6—17 are from younger embryos than that reconstructed in Pl. 38, 
fig. 1. 
Figs. 6 and 7.—Cross-sections through the vagus myotome and ganglion. 
Fig. 7 is posterior to Fig. 6. 
Fic. 8.—Cross-section between the second and third myotomes. 
Fic. 9.—Cross-section between the fourth and fifth myotomes. 
Fic. 10.—Cross-section showing the first protoplasmic prolongations at the 
root of the motor nerve. 
Fie. 11.—Cross-section through the fifth myotome, showing the distribu- 
tion of yolk granules in the tissues of the trunk at the time when the neural 
crest forms. 
Fic. 12.—Cross-section between the fourth and fifth myotomes in an 
embryo older than that of Fig. 9. 
Fie. 13.—Cross-section through the ventral root of the fifth spinal nerve. 
Fies. 14 and 15.—Cross-sections through the ventral roots of the fourth 
spinal nerves. 
Fic. 16.—Cross-section through the root of the tenth spinal nerve. 
Fic. 17.—Cross-section showing the beginning of the motor root of the 
third spinal nerve. 
Fie. 19.—Section through the lateral line ridge of an embryo at the stage 
of development given in PI. 38, fig. 1, where the plane of the section is marked. 
Fic, 20.—Section through the skin of the embryo of Fig. 18, where the 
plane of the section is given. 
