SHORK P-ISHKS OF f;ALAPAGOS ISLANDS 363 



a rid^e-like spine, these increasing in size posteriorly, forming on 

 caudal peduncle a high sharp lateral crest; spirje-bearing scales not 

 more than thirty in number ('30 in one specimen, 28 in another). 

 Posterior ones lapping over one another, forming a high hard longi- 

 tudinal ridge along the side of the caudal peduncle; in front of the 

 caudal peduncle they decrease regularly in size, and the most anterior 

 is a mere rudimentary projection on the posterior margin of the scale 

 the most anterior of the spine-bearing scales scarcely at all enlarged; 

 posteriorly they increase in size with increase in the size of the spines. 



Valenciennes represents about 40 enlarged plates on the straight 

 posterior part of the lateral line ; his figure, however, does not show 

 the spines of the scales. Jordan and Evermann {Fishes N. & M. A.^ 

 /, -pp. Q07, Q08 ) have grouped Decapterus sco7nbrinus with D. 

 puJictatus, the 2 being characterized by having 40 or more enlarged 

 plates on the lateral line. D. hypodus Gill, has 30 enlarged plates 

 on the lateral line and is otherwise very similar to D. scombrinus, 

 but it has been described by Gill {Proc. Acad. Nat. Sci. Phila. 

 1862, 26) and by Jordan and Gilbert {Proc. U. S. Nat. Mus. 

 1882., Js8) as being very closely related to D. macarellus. There can 

 be no doubt, however, that hypodus and scombrlnus are very closely 

 related and it is not improbable that hypodus (1S62) may prove to be 

 a synonym of scombrlnus (1846) . D. hypodus is recorded only from 

 Cape San Lucas. 



Color of fresh specimen. — Above, light olive-green, fading to 

 silvery-white on the sides; fins dusky; upper half of caudal olive- 

 yellow; dusky below; a dark semilunar spot on posterior margin of 

 opercle above posterior angle. 



MEASUREMENTS, FIN RAYS AND SCALES OF Decaj}teruS SCOm- 



brinus. 



Length in mm 304 l^ 



Depth 23 22 



Head 27 2S 



Pectoral 24 22 



Eye ° , 7 



Number of dorsal spines VIII-I VIII-I 



Number of second dorsal rays 33"' 33-' 



Number of second anal rays 26-1 27-1 



Number of spine-bea ring scales of lateral line 30 28 



49. TRACHURUS SYMMETRICU.S (Ayres). 



Caranx symmetricus Avres, Proc. Cal. Acad. Sci., i, 1855, 62, San Francisco, 

 Caranx {Trachurus) cuvieri Steindachner, Ichthyol. Beitr., 11, 16, 1875, 

 Talcahuano, Callao, Juan Femandes, Galapagos. 



