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EDWJN S. GOODRICH. 
Diagram 5. — Three figures illustrating the principle of transposition 
as seen in the development of median fins. From the myotonies m are 
derived the radial fin-muscles r.w. 1-11 branches of spinal nerves. 
Diagram 6. — The head-region of an Amphibian A, and an Amniote 
^(mammal) B. The broken line o-o indicates the hind limit of the 
occipital region. 1-7 myotomes. a. Auditory capsule, hr.s. Bronchial 
-slit. /. Facial nerve. Glosso-pharyngeal. h. Hyj)Oglossal. h.m. 
Hypoglossal musculature, n.a. Neural arch. n.c. Nasal capsule, o.p. 
Optic capsule, s. Tympanum, s.g. Vestigial spinal ganglion, s. o. 
First metaotic somite, sp. Spinal nerve. tr\ Profundus, fr- Tri- 
geminal. V. vagus nerve. 
