ALEPISAUROID AND MYCTOPHOID FISHES 329 



during active movements. Perhaps the sudden raising of the dorsal gives stability during turns and 

 enables turning to be more rapidly effected, a capacity that may well be important in a fish which 

 preys on such large active fishes as the paralepidids. 



EM 



Text-fig. 8. Dorsal fin of Alepisaimis ferox: a, the basal elements supporting the first three dorsal rays. DM, EM, IM, 

 depressor, erector and inclinator muscles of fin-ray (X4/5); b, the basal elements supporting the 14th and 15th dorsal 

 rays ( x 7-5). 



Intermuscular bones 



In his Classification of Fishes, Berg (1947) remarks that in the lower teleosts true intermuscular 

 bones (epineurals, sometimes also epicentrals) are usually present. In defining the larger groups, 

 Berg states that intermuscular bones are present in the Isospondyli, Haplomi, Ostariophysi (Cypri- 

 noidea) and Apodes. (Definite absence is recorded for the gadoids, Solenichthyes, Microcyprini and 

 Percomorphi.) 



Intermuscular bones are also present in certain of the alepisauroid fishes. Hubbs, Mead and 

 Wilimovsky (1953) observed the prominent development of these bones in Anotopterus and Alepi- 

 saurus and described the complex as consisting of a series of thick dorsal elements running hori- 

 zontally, together with more slender median bones stretching backward and slightly downward. The 

 positions of the intermuscular bones in a transverse section across a medium-sized individual of 

 Anotopterus pharao may be seen in Text-fig. 9 a. The pattern of intermuscular bones in Alepisaurus is 

 remarkably similar to that found in Anotopterus. 



Certain of the Paralepididae and Omosudis lowei also have intermuscular bones, which are developed 

 in both the epaxial and hypaxial parts of the myotomes. A drawing of the more conspicuous elements 

 associated with the first three vertebrae of Omosudis may be seen in Text-fig. gb. The extraordinary 



4-2 



