CONTENTS. 



PAGE. 



Section i. — Introductory i 



I, — General Introduction i 



II.— Introductory Sketch of the Theory of Nerve Com- 

 ponents 7 



III. — Scope and Methods i9 



Section 2. — The Lateral Line Canals and their 



Organs 25 



I.— The Lateral Lines 25 



I,— The Lateral Line of the Trunk 27 



2.— The Lines of the Head 28 



3. — The Extra- scapular Canal 29 



i. — The Post-occipital Main Canal 29 



//.—The Occipital Commissure 29 



4.— The Squamosal Canal 1'^ 



5._The Opercular Canal 30 



6.— The Mandibular Canal 31 



7. —The Infra-orbital Canal 32 



8. — The Supra -orbital Canal 33 



II.— Accessory Lateral Line Organs 34 



III. — Comparative 37 



IV.— Summary of the Lateral Lines 43 



Section 3. — The Central Relations of the Cranial 



Components 44 



L— The General Cutaneous System 44 



II.— The Acustico-lateral System 48 



III.— The Communis System 50 



IV.— The Motor Components 65 



v.— Summary of Section 3 66 



Section 4. — The Spinal Nerves 67 



I.~The Fourth Spinal Nerve ^7 



II.— The Third Spinal Nerve 69 



III.— The Second Spinal Nerve 7o 



