BY J. DOUGLAS 0«ILBY. 761 



with two patches of teeth anteriorly and a long narrow band on 

 the shaft; bands of teeth on the palatines, pterygoids, and tongue. 

 31 to 33 gill-rakers on the lower branch of the anterior arch, the 

 longest 2 to 2^- in the diameter of the eye. Origin of the first 

 dorsal a little in advance of the middle of the pectoral, the third 

 or fourth ray the longest, It to 2 in the head, the two last almost 

 concealed in the dorsal groove; second dorsal originating a little 

 nearer to the base of the caudal than to the extremity of the 

 snout, the anterior rays the longest, not so long as those of the 

 first dorsal : free anal spines moderately strong : ventral not 

 reaching midway to the vent, the second ray the longest, 2y\i- to 

 23- in the head : pectoral with 23 to 25 rays, extending to or a 

 little beyond the vertical from the sixth dorsal spine, its length 

 If to H in the head : caudal small, 5|- to 6i in the total length. 

 Cheeks, occiput, and breast scaly; two series of scales extending 

 forward along the middle of the interorbital region; preorbital 

 and preopercle with radiating muciferous canals. Lateral line 

 gently curved to below the twelfth dorsal ray, the straight part 

 shorter than the curved, with 25 to 28 spinose plates. 



Blue above, silvery below the lateral line; a small black oper- 

 cular spot: dorsal, caudal, and pectoral fins dotted with black. 



Etymology : — Xe-n-ros, slender; aafin, body. 

 Distribution : — Port Jackson. 



Our Mackerel-Scad is known to the fishermen as a " small kind 

 of Cowanyung," which is not so far astray, the true " Cowanyung " 

 being, as far as can be conjectured from the description given to 

 me, the adult Yellowtail {Trnchurus declivis) or some closely 

 allied species. It is said to visit the coast ever}^ spring, aind 

 enters the harbours in company with the half-grown Yellowtails, 

 but not nearly in the same numxbers, only a few Cowanyung — 

 restricting that name to the Decaptenis — being found in a school 

 of Yellowtail. My largest examjDle measures 170 millimeters, 

 and I am told that it rarely exceeds this length. 



This species difliers greatly from Decapterus Jwhern, Hector, 

 and D. ecc/ipsifer, DeVis. 



