40 PAPERS FROM TORTUGAS LABORATORY vol. xxxiv 



Syacium Ranzani, 1840 



The two Tortugas species of Syacium apparently are not separable from a 

 single feature, but on the basis of multiple characters they are distinguishable 

 without difficulty. 



Syacium papillosum attains the larger size, generally is more slender, shows 

 sexual dimorphism in color not shown by S. gunteri, has more accessory scales 

 than S. gunteri at the same size, and usually has the larger number of scales in 

 the lateral line, and a greater number of dorsal and anal rays. Of S. papillosum, 

 in a sample of 99 from Tortugas, 1 specimen has fewer than 84 dorsal rays, but 

 of S. gunteri, in a sample of 31, only 1 specimen has more than 84. Approximately 

 50 per cent of the species first named have 86 to 88 dorsal rays, and 50 per cent 

 of the second have 78 to 80 dorsal rays (see tables). Depth of body in standard 

 length 2.2 to 2.4 in S. papillosum, and 1.8 to 2.0 in S. gunteri; scales in lateral line 

 about 50 to 56 in S. papillosum and 44 to 51 in S. gunteri. W. H. L. 



Syacium papillosum (Linnaeus) 



Very common in 10-fathom channels, also in slightly deeper water to the east 

 of Bush Key and Bird Key reef; abounding at the depth of 40 fathoms, south of 

 Tortugas, extending its range to 60 fathoms. 



Males (at Tortugas) are not white on the blind side but more or less cinereous, 

 at about 150 mm. in length and upward. Half-grown males and older ones differ 

 besides from females by having before the right eye two parallel lines of blue 

 running toward the tip of the snout, though the one nearest the dorsal outline 

 is blotted out anteriorly on the blind side. Much more confusing is the fact that 

 both sexes vary greatly in appearance, as the surroundings vary from which they 

 come. Off gray muddy bottom in 40 to 60 fathoms they are nearly plain gray, 

 but from the more brilliantly illuminated bottom in 10 to 15 fathoms they vary 

 in ground color from cream-buff to drab and are highly variegated.' The pattern, 

 however, is rather constant, including three dusky areas along the lateral line 

 (the foremost just before its point of inflection, the anterior margin of the next 

 equidistant from tips of snout and tail, the last just before base of caudal 

 peduncle; the first nearly circular, the second and third more extended respectively 

 in the transverse and long axes); body also with many circular pale spots with 

 dark centers; almost a score of pale spots on median fins; body and fins also with 

 many minute dark dots; pectoral fin crossed by three bars. 



In the belief that the color of this species is "nearly plain brown, with darker 

 dots or mottlings, no ringlike spots or ocelli," some students have assigned to 

 Syacium micrurum specimens really belonging to S. papillosum. 



The food consists largely of small crustaceans. 



West Indies to Florida. W. H. L. 



