MACKEREL. 



Ill 



Mode, Clirist., 1808, p. 520: Mai,m, 6'%s', Boh. Fa., p. 

 408; LiLi.j., A'ii., Nor<j. Fiskar, vol. I, p. 224; Jonu., Gilb., 

 ^l/n. Fish. N. Amer., Bull. U. S. Nat. Mns., No. 16, p. 424; 

 Bit. (iooi)K. F/'sh. Iiulii.-'Ir. U. S., part. I, p. 281, tab. 91. 

 Scomber sconibci; LiN., H'/st. Nat., ed. XII, torn. I, p. 492; 

 (iTiiH, Vat. Brit. Mils., Fish., vol. II, p. 367; Cull., Vid. 

 Selsk. Forli. Christ. 1874, Tilbcgsh., p. 43; 1879, No. 1, 

 p. 18; WiNTHER, Nntnrli. Tidskr. Kblivn, ser. 3, vol. XII, 

 p. 12; Id., ZooI. Dan., Fi.sli-e, p. 21, lab. IV, fig. 3; Day, 

 Fi.sli. G:t Brit., Irel., vol. I, p. 83, tab. XXXII et XXXIIl 

 {var. punctatii-:): Mdn., IIcke, Fischc d. O.'ilsc'C, p. 38. 



The t'orni of the body is handsome, elongated, 

 terete and shallo\\': it tapevs almost ecjuall}' at hoth 

 ends. The greatest depth, which is generally situated 

 at the end of the first dorsal fin, varies according to 

 age and sex between 15% and 20% of the length. The 

 greatest breadth, which is situated at the same j)oint, 

 is somewhat more than "/g of the greatest depth. Both 

 the back and the belly are broad and convex, but the 

 dorsal line is almost straight from the occiput to the 

 second dorsal tin, from which point it slopes down to- 

 wards the caudal fin. The ventral line, on the other 

 hand, runs fairly evenly in a sliglit curve from the 

 point of the lower jaw to the l)ase of the caudal tin. 

 The head is cuneiform, triangularly pointed and middle- 

 sized. During the first year and up to the spring of 

 the second its length is somewhat over ^/^ (between 

 27 % and 25 %;) of the length of the body; it then sinks to 

 about 23 %; but after the third year it apparently rises 

 again to about 24 %. The perpendicular draAvn from 

 the occi])ut to the isthmus through the hind margin of 

 the orbit is about half the length of the head, and the 

 breadth of the latter, measured above the hind margin 

 of the orbit, is equal to the distance between the tip 

 of the snout and the anterior margin of the pupil. 

 The breadth of the interorbital space at the middle of 

 the eyes is on an average about 42 % of the length of 

 the lower jaw up to the end of the first year, during 

 the second year about 46 % and afterwards about 57 %. 

 The snout elongated and pointed; the mouth of average 

 size. The jaws are of ecjual length; when the mouth 

 is open, tlie lower seems longer than the upper; l)ut 

 when the mouth is closed, it glides under the broad, 

 flat preorbital bones. At the margin of the inter- 

 maxillaries is a simple row of tine, pointed teeth of 

 equal size, which are sparsely set and somewhat re- 

 curved. A .similar row of teeth also occurs at the 

 margin of the lower pw. The pharyngeals, too, are 

 covered with long, setiform teeth, and there are al)out 

 44 long gill-rakers on the front of the first branchial 



arch. At the margin of each |)alatine bone is a row 

 of very small teeth, and laterally at each end of the 

 head (jf the vomer we find from 2 to 4 somewhat 

 larger teeth. The tongue is small and smooth, with 

 the point free. The e\-cs of average size and set high; 

 the diameter of the (jrbit measures about V.'i of the 

 length of the head. They are covered with a thin, 

 transparent membrane, which, however, seems to grow 

 thicker toward winter. Tiiis membrane — the so- 

 called adi|)()sc lid, though there is no fat whatever in 

 it (see above) — extends along the side of the head 

 and envelops the eyeball, but ahvays leaves uncovered 

 a per])endicular slit al)ove the pu|iil. The anterior flap 

 is continued some way over the posterior at the lower 

 margin of the eye. The anterior nostril is, as usual, 

 a r<Miud hole, and lies half-way between the tip of the 

 snout and the anterior margin of the pupil: the poste- 

 rior, as is also generally the case in the Scombridte, 

 is a perpendicular slit, situated half-way between the 

 anterior nostril and the antei'ior margin of the pupil. 

 The apparatus of the gill-cover is made up of thin bones 

 with .smooth margins: the hind margin of the oper- 

 culum is somewhat incised, its length (in the direction 

 of the body) is about 7, (from 20 to 22 %) of the 

 length of the head: along the preoperculum it is elong- 

 ated downwards, over the suboperculum, into a point. 

 The breadth of the back part of the interoperculum 

 varies between 13 % and 16 % of the length of the head. 

 The rounded lower coi'uer of the preoperculum is elong- 

 ated posterioi'ly in a downward direction. The .striation 

 of the mai-gin of the preoperculum \vhich we have ob- 

 served above in Sarda pelamis, is not quite absent in 

 this species, but is far more indistinct. The gill- 

 openings are large. The branchiostegal membrane, 

 which is free (not fastened at the isthmus) is supported 

 by 7 rav!? on each side, the last two of which lie close 

 together under the gill-cover. 



The body is covered with very small scales, which 

 on the silvery belly can scarcely be distinguished with the 

 naked eye; in the region of the pectoral fins and along 

 the clavicular bones, the posterior boundary of the gill- 

 openings, they are somewhat larger, but form no distinct 

 corslet. The lateral line, which lies much nearer the back 

 than the belly, begins at the upper margin of the gill- 

 opening and extends in a sinuous line to the middle of 

 the caudal fin. Tiic vent is situated at the beginning 

 of the last third of the length of the body, measured 

 from the tip of the snout to the base of the caudal fin. 



