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Show 878 MR. WALTER E. COLLINGE ON THE SENSORY [Dec. 17, supposed to feed on birds' eggs and small birds. It is very rare indeed, and is obtained with much difficulty." EXPLANATION OF PLATE L. Fig. 1. Ceenolestes obscurus. Outline of skull; natural size. 2,3,4. ,, „ Side, upper, and lower views of skull, twice natural size. 5. ,, „ Cheek-teeth, side view; magnified 5 times. 6. „ „ Upper teeth and half palate. do. 7. „ ,, Lower do. do. 8. Decastis columnaris. Left ramus, lower jaw (after Ameghino). 9. Parepanorthus minutus. do. do. 2. On the Sensory and Ampullary Canals of Chimcera. By W A L T E R E. COLLINGE, F.Z.S., Assistant Lecturer and Demonstrator in Zoology and Comparative Anatomy, Mason College, Birmingham. [Received November 14, 1895.] (Plates LL-LLTI.) CONTENTS. Page I. INTRODUCTORY , 878 II. T H E SENSORY CANAL-SYSTEM 879 1. General Description 879 2. Course of the Canals and Branches 880 3. Structure and Histology of the Canals 881 4. Innervation 882 III. T H E AMPULLARY CANALS 884 1. General Description 884 2. Structure and Varieties 886 3. Innervation 887 IV. SUMMARY A N D CONCLUSION 887 V. COMPARISON WITH :- 1. Elasmobranchii "j 2. Ganoidei I Table facing 888 3. Teleostei J VI. BIBLIOGRAPHY 888 EXPLANATION OF T H E PLATES 889 I. INTRODUCTORY. Previous references to either the sensory and ampullary canals or cranial nerves of Chimcera are few. There are a number of papers-all more or less imperfect-dealing with the central nervous system, dating from Valentin's studies of 1842. Stannius (17) in 1849 described and figured in his classical work the cranial nerves of Callorhynchus, a genus closely allied to Chimcera. There are also brief references in the text-books of Huxley, Gegenbaur, Wiedersheim, and others. The earliest reference to the canal-system is that given by Leydig (12) in 1851. Hubrecht (11), |