62 ELOPIFORM FISHES 



particularly in its dorsal extent, and situated anterior to the reduced neural spine 

 associated with the neurocranial centrum. As in Elops (p. 25) there is an overlapping 

 of the supraneural and pterygiophore series. 



Median fins. The dorsal fin is situated in the centre of the back and is composed 

 of 15 (13-15) fin-rays, of which the first two are unsegmented. The sixth ray is the 

 first branched. Behind the sixth the rays decrease in length except the last, the 

 posterior half of which is produced into a long filamentous structure (see p. 201). 

 The lepidotrichs are supported by 12 pterygiophores, each composed of proximal, 

 middle and distal radials. The first pterygiophore is considerably stouter than 

 those succeeding it, and proximally it extends between the tips of the neural arches 

 of the twenty-first and twenty-second vertebrae. 



The origin of the anal fin lies nearer to the pelvic than to the caudal peduncle. 

 The fin is composed of approximately 24 rays (range 22-25), 0I which the first four are 

 unsegmented. The eighth is both the longest and the first branched ray. The 

 posterior rays increase in length. The posterior half of the last ray may be produced 

 as a short filament (in alcohol-preserved specimens the tips of the fin-rays are often 

 broken). The fin-rays are supported upon approximately 21 pterygiophores. The 

 first, which supports four rays, extends antero-dorsally to end immediately beneath 

 the thirty-first centrum. 



The caudal fin has been described and figured by Hollister (1936). 



Squamation. The structure of the scales has been dealt with by Hollister (1939) 

 and Cockerell (1912). Consequently only brief mention of them is made here. 



There are 41-48 lateral line scales (in specimens examined the mode was 44). 

 The transverse count in front of the dorsal fin is 5/6. Scales of the lateral line are 

 rounded, the transverse and horizontal axes being equal. The anterior border shows 

 three scallops delimited by four radii which extend to the centrally placed nucleus. 

 The tube containing the lateral line has secondary branches, which do not anastomose 

 (cf. Megalops). 



The general body squamation shows a variation in the scale shape. Those scales 

 immediately behind the cleithrum are deeper than long ; those upon either side of 

 the dorsal mid-line are decidedly longer than deep while those on the caudal 

 peduncle are only slightly longer than deep. The scales which sheath the base of 

 the anal fin (there are no sheathing scales on the dorsal fin, cf. Elops) are smaller 

 than other body scales and are ovoid to irregular in shape. 



Despite differences in shape the scale ornamentation remains constant. The 

 embedded portion of the scale is marked by concentric circuli composed of many 

 partially fused tubercles. In the exposed portion the circuli break up to an ir- 

 regular pattern of tubercles. The posterior margin of the scale is very thin, un- 

 marked by circuli or tubercles. Instead the border is finely crenulated. In large 

 scales (i.e. those of large individuals) the posterior scale margin is frequently frayed. 



An exception to the above scale types is the scale at the axis of the pelvic and 

 pectoral fins. The axillary scale is elongate, two and a half times as long as deep, 

 rounded anteriorly, pointed posteriorly. The scale is attached to the body wall by 

 a thick flap of skin which inserts on the medial face of the posterior half of the scale. 

 Circuli are absent and the radii, which originate from the anteriorly placed nucleus, 



