SCIENTIFIC SURVEY. 



2T 



classification which he adopted by which it will be seen that the 

 first or primary divisions are those of Belon — the second his own, 

 and the third those of Linneus : 



Sub-Classes. 



ri. 



Cartilaginous Fishes. — 

 The spine composed of- 

 cartilaginous vertebras. 



I 



r5. 



Osseous Fishes. — The 

 spine composed of bony 

 vertebrae. 



Divisions, 



1. No operculum nor branchial 

 membrane. 



2. No operculum, but a branchial 

 membrane. 



r 1. 

 2. 

 3. 

 4. 

 5. 

 6. 

 7. 



3. An operculum; no branchial 

 membrane. 



4. An operculum, and a bran- J 14 



chial membrane. 



9. 

 10. 

 11. 

 12. 

 13. 



15. 

 16. 



ri7. 



1. An operculum and a branchial I 18 



1 S in 



membrane, 



2. An operculum; no branchial 

 membrane. 



3. No operculum, but a branchial 

 membrane. 



4. Neither operculum nor bran- 

 chial membrane. 



19. 

 20. 



r2i. 



22. 

 23. 

 24. 

 25. 

 26. 

 27. 

 28. 

 29. 

 30. 

 31. 

 32. 



Orders. 



Apodal. 



Jugular. 



Thoracic. 



Abdominal. 



Apodal. 



Jugular. 



Thoracic. 



Abdominal. 



Apodal. 



Jugular. 



Thoracic. 



Abdominal. 



Apodal. 



Jugular. 



Thoracic. 



Abdominal. 



Apodal. 



Jugular. 



Thoracic. 



Abdominal. 



Apodal. 



Jugular. 



Thoracic. 



Abdominal. 



Apodal. 



Jugular. 



Thoracic. 



Abdominal. 



Apodal. 



Jugular. 



Thoracic. 



Abdominal. 



Practical application of these Systems as aids to Study. 



We will not spend any more time in the review of the several 

 systems of classification which have heretofore been adopted by 

 the several writers in question. They are all of them based partly 

 upon the existence or non-existence of certain organs without ref- 

 erence to their structures or uses. This, as has been remarked, 

 while it did much better than none, and aided, not only the writer 

 in establishing something like method in his work, also aided the 

 student in his researches or studies, as far as merely ascertaining 

 the place in the system of the individual specimens found, and the 

 names given them. This may be thus illustrated in reference to 

 either of the foregoing systems given. Take for instance the last 

 named one (Lacepede's.) 



Suppose the student to have before him the five volumes of that 



