188 ELOPIFORM FISHES 



23. Opercular apparatus complete, with a large suboperculum and large inter- 

 operculum. 



24. Pectoral girdle with a mesocoracoid arch articulating ventrally with both the 

 scapula and coracoid. 



25. Coracoid large. 



26. Pectoral fin held low down on the body. 



27. Pelvic fin abdominal, held horizontally, with more than 10 rays. 



28. Pelvic splint bone present. 



29. Vertebral centra pierced for the passage of the notochord. Neural arches, 

 haemal arches and parapophyses autogenous. 



30. Neural spines in the anterior abdominal region composed of separate lateral 

 halves. 



31. Supraneurals forming a complete series between the occiput and the origin 

 of the dorsal fin. 



32. Epineural intermuscular bones developed throughout the column. 



33. Caudal fin forked. 



34. Caudal skeleton with two free ural centra, uroneurals free from centra, 

 hypurals separate from one another and from the ural centra. Parhypural 

 without a hypurapophysis. 



35. Nineteen principal caudal fin-rays ; 10 in the upper lobe, 9 in the lower. 



36. Scales cycloid, with bone cells. 



37. Lateral line complete. 



38. Swimbladder with anterior outpushings developed on either side of the mid- 

 line. 



39. Retroarticular absent. 



40. Development of a leptocephalus larva. 



41. Rostral ossicles present. 



42. Pectoral splint present at the base of the outermost fin-ray. 



43. Basipterygoid process absent. 



44. Mesethmoid weakly ossified or absent. 



45. Ectopterygoid process present (its development varies within the order). 



46. Supraorbital and infraorbital canals connected above the sixth infraorbital. 



In addition, there are many other primitive characters found in the basal family 

 (the Elopidae) of the order. These are listed below : 



47. Body fusiform, showing little compression, fins acuminate. 



48. Cranium shallow, mouth terminal. 



49. Neurocranium shallow, skull roof flat. 



50. Cephalic sensory canals enclosed by bone. 



51. Supraorbital sensory canal extending to the parietal. 



52. Dilatator fossa with roof. 



53. Ethmoid commissure complete, contained within a bony tube that runs 

 across the dermethmoid. 



54. Intercalar large, and with the prootic forming an intercalar-prootic bridge. 



