STUDIES OF ALEPISAUROID FISHES 



By N. B. Marshall 

 (Plate XIX and Text-figs 1-9) 



INTRODUCTION 



THE Alepisauroidea are voracious, bathypelagic fishes which together with the Myctophoidea 

 form the order Iniomi. 



Fishes of the order Iniomi are soft-rayed teleosts, which have evolved beyond the level of the Isospon- 

 dyli in that the premaxillaries exclude the maxillaries from the gape. The pelvic fins are usually 

 abdominal in position, but when they are set close to the pectorals, as in the Aulopidae, there is no 

 association between the pelvic bones and the pectoral girdle. The swim-bladder when present is 

 closed (physoclistous) and the blood supply to the retia mirabilia enters at the anterior end. There are 

 usually 19 principal rays in the caudal fin and 6-1 1 rays in each pelvic fin. The dorsal fin and anal fin 

 are never opposed and an adipose dorsal fin is usually present. There is no mesocoracoid, nor is a 

 Weberian mechanism present. 



The Alepisauroidea can be defined as bathypelagic Iniomi with no swim-bladder or luminescent 

 organs, with a single row of numerous (more than 20) small teeth on each premaxillary, one or two 

 rows of teeth on each palatine, one to three rows of teeth on each dentary and with gill-rakers in the 

 form of spines or teeth. The anal fin has from 12-50 rays and is usually set close to the caudal. Lastly, 

 there are 3-4 + 4-5 branchiostegal rays. 1 



Compared with most other oceanic, mid-water teleosts, the Alepisauroidea are large, even very 

 large, fishes. 2 Owing to their size and swiftness, our knowledge of this suborder of the Iniomi — at 

 least from catches of mid-water nets — is very incomplete. Almost without exception, the larger 

 known individuals of the larger species have come either from the stomachs of whales or of oceanic 

 fishes, such as tunny, or have been taken on long lines. Alepisaarus itself, which is caught on the 

 tunny hooks of Madeiran fishermen, has contained some relatively large paralepidids. 



This report is based mainly on specimens from the Discovery Collections. The material contains 

 some new species and is sufficiently extensive to allow of a revision of the Scopelarchidae and a review 

 of the relationships of the alepisauroid fishes. 



ACKNOWLEDGEMENTS 



My thanks are due to Dr N. A. Mackintosh for putting the material at my disposal and to Dr W. A. 

 Gosline, who has read the manuscript and made some useful critical comments. 



1 The plus sign separates the rays on the epihyal and ceratohyal bones. 



2 Alepisaurus reaches a standard length of at least 1500 mm.; the largest known Anotopterus is 855 mm. in length, while 

 three paralepidids, Magnisudis barysoma, Notolepis coatsi and Sudis hyalina, fall within the standard length range of 400-500 mm. 

 Certain other paralepidids, Omosudis lozuei, Evermannella balbo and Neoscopelarchoides elongatus, grow to within the range 

 150-300 mm. 



