PISCES. 201 



copterygii), or with spinous rays {Acanthopterygii), and fishes with ])oneless 

 branchiae (Branchiostegi). Fifty-eight genera were distributed under these 

 four heads, corresponding for the most part with those of Linnaeus, whose 

 arrangement comes next in order. This is based upon the position of the 

 vertical fins, or the structure of the gills. The following tabular view 

 exhibits the orders of Linnaeus, with the genera of each order, taken from 

 the thirteenth edition of 1767. 



I. Apodes. Ventral fins none. 



1. Muraena. 4. Anarhichas. 7. Stromateus. 



2. Gymnotus. 5. Ammodytes. 8. Xiphias. 



3. Trichiurus. 6. Ophidium. 



II. JuGULARES. Ventral fins before the pecto7'al. 



9. Callionymus. 11. Trachinus. 13. Blennius. 



10. Uranoscopus. 12. Gadus. 



III. Thoracici. Ventral fins under the pectoral. 



14. Cepola. 20. Zeus. 26. Perca. 



15. Echineis. 21. Pleuronectes. 27. Gasterosteus. 



16. Coryphaena. 22. Chaetodon. 28. Scomber. 



17. Gobius. 23. Sparus. 29. Mullus. 



18. Cottus. 24. Labrus. 30. Trigla. 



19. Scorpaena. 25. Sciaena. 



IV. Abdominales. Ventral fins behind the pectoral. 



37. Fistularia. 43. Mormyrus. 



38. Esox. 44. Exocaetus. 



39. Elops. 45. Polynemus. 



40. Argentina. 46. Clupea. 



41. Atherina. 47. Cyprinus. 



42. Mugil. 



The remaining genera were arranged under the head of Amphibia, as 

 Amphibia nantes, and characterized by having fixed gills without a bony 

 structure. 



V. Spiracula Composita. 



48. Petromyzon. 50. Squalus. 51. Chimaera. 



49. Raja. 



VI. Spiracula Solitaria. 



52. Lophius. ."}6. Ostracion. 59. Centriscus. 



53. Acipenser. 57. Tetraodon. 60. Syngnathus. 



54. Cyclopterus. 58. Diodon. 61. Pegasus. 



55. Balistes. 



405 



