878 ME. WAMEE B. COLLINGTE ON THE SENSOET [DeC. 17, 



means ' Opossuin-Eafc.' It lives in the high brush-wood, and is 

 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. Catwlestes obscurus. Outline of skull ; natural size. 



2, 3, 4. ,, „ Side, upper, and lower views of skull, twice 



natural size. 

 6. „ „ Cheek-teeth, side view ; magnified 5 times. 



6. „ „ Upper teeth and half palate. do. 



7. ,, ,, Lower do. do. 



8. JDecastis columnaris. Left ramus, lower jaw (after Ameghino). 



9. Parepanorthus minutus. do. do. 



2. On the Sensory and Ampullary Canals of Chimcera. By 

 Walter E. Collinge, F.Z.S., Assistant Lecturer and 

 Demonstrator in Zoology and Comparative Anatomy, 

 Mason College, Birmingham. 



[Eeceived November 14, 1895.] 



(Plates LI.-Lni.) 



Contents. 



Page 



L INTEODDCTORY 878 



IL The 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. The Ampullary Canals 884 



1. General Description 884 



2. Structure and Varieties 886 



3. Innervation 887 



IV. SuMJiAKY and Conclusion 887 



V. Comparison with : — 



1. Elasmobranchii 1 



2. Ganoidei I Table facing 888 



3. Teleostei J 



VI. Bibliography 888 



Explanation op the Plates 889 



I. Inteoductoet. 



Previous references to either the sensory and ampullary canals 

 or cranial nerves of Chinicera 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 Calloi-hynchus, a genus closely allied to Chimoira. 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), 



