20 MUEJENIDJ3. 



a. Nostrils superior or lateral ; tongue free ; end of the tail sur- 



rounded by the fin. 



a. Pectoral fins present D. Angitillina. 



Skin with nidinientarj scales ; teeth in bands ; tlie dorsal fin commences at a 

 considerable distance from the occiput 4. Anguilla, ^.'lo. 



Scaleless. Jaws with an outer series of closely set teeth ; dorsal fin commencing 

 behind the base of the pectoral ; mouth extending at least to below the middle 

 of the eye 5- Coyigcr, -^.'31. 



Scaleless. Fore part of the skull with large muciferous cavities. Teeth forming 

 bands ; dorsal fin commencing nearly above tlie gill-opening ; mouth not ex- 

 tending beyond the middle of the eye 6. Congromurmna, p. 40. 



Scaleless. Maxillary teeth biserial, vomerine teeth uniserial ; dorsal fin com- 

 mencing above the root of the pectoral ; mouth extending slightly beyond the 

 middle of the eye 7. f/Voww^CT-, p. 43. 



/3. Pectorals none E. Hetekocongrina. 



Exceedingly elongate ; snout very short 8. Heteroconger, p. 44. 



b. Nostrils superior or lateral ; tongue not free ; end of the tail 



surrounded hy the fin F. Mur^snesocina. 



Pectoral fins ; jaws with canine teeth in front ; vomer with large, strong teeth. 



9. Murancsox, p. 45. 



Pectorals none. Posterior nostril superior, above the angle of the orbit. 



10. Nettastoma, p. 48. 



Pectorals none. Posterior nostril lateral, in front of the orbit. 



11. Saurenchelys, p. 48. 



Pectoral fins. Teeth of the jaws triserial, the middlg series containing long 

 canine teeth ; vomer with a series of very small teeth. 



12. Oxyconger, p. 48. 



Pectoi-al fins. Teeth of the jaws biserial ; vomer with a series of very long 

 teeth 13. Hophmnis, ■p. 'i!d. 



Pectoral fins. Dorsal and anal fins rudimentary. 14. Neoconger, p. 49. 



C. Nostrils labial ; tongue not free ; end of the tail surrounded 

 bij fJiefiu G. Myrina. 



Pectorals well develojoed ; dorsal commencing behind the gill-opening ; teeth in 



bands 15. Mgncs, -p. -iQ. 



Pectorals well developed ; dorsal commencing far behind the pectorals. 



16. jSIyrophis, p. 50. 

 Pectorals well developed ; dorsal commencing behind the giU-opening ; teeth in 



tne jaws biserial 17. Pammgrits, p. 51. 



Pectorals nearly invisible. Body short, much compressed. 



18. Chilorhiniis, p. 51. 



Pectorals none. fJody long, vermiform 19. Murmnkhthys, -p. hi. 



d. Nostrils labial ; tongue not free; end of the tail free. 



H. Ophichthtina. 



Vomerine teeth none 20. Liuranus, p. 54. 



Vomerine teeth 21. Ophichthys, p. b^. 



III. TJie tail is much shorter than the trunk. The heart is situated 

 at a great distance behind the gills . . I. Ptyobranchina. 



Pectorals none or small ; vertical fins but little developed. 



22. Moringua, p. 90. 



