74. SCOMBRIDJE SCOMBER. 423 



pointed anteriorly. Mouth rather large; premaxillary not protractile ; 

 maxillary without supplemental bone; jaws with sharp teeth, large or 

 small. Yomer and palatines toothed or not. Preopercle entire ; opercle 

 unarmed. Gill-openings very wide, the membranes not united, free from 

 the isthmus. Gill-rakers usually long. Pseudobranchiae present, large. 

 A slit behind fourth gill. Branchiostegals 7. Dorsal fins 2, the first 

 of rather weak spines, depressible in a groove, the second similar to the 

 anal; anal spines weak; last rays of dorsal and anal usually detached 

 and separate, forming series of finlets ; caudal peduncle extremely slender, 

 usually keeled, the caudal lobes abruptly diverging, falcate; ventral tins 

 moderate, thoracic, 1, 5. Vertebrae in greater number than in Carangidce, 

 the number more than 25. Pyloric cceca numerous. Air-bladder fre- 

 quently absent. Coloration metallic, often brilliant. General?; species 

 about 70. Fishes of the high seas, many of them cosmopolitan, and all 

 having a wide range. Most of them are valued as food-fishes. 



(Scombrldce pt. and Trichiuridce pt. Gimther, ii, 349-373.) 



a. Fiulets present ; dorsal spines less than 20. (Scombrhiw.') 



6. Spiuous dorsal short (of less than 12 spines), remote from the second. 



c. Vomer and palatines with teeth; corselet obsolete SCOMBER, 213. 



cc. Vomer and palatines toothless; corselet well developed Auxis, 214. 



&&. Spinons dorsal long (of more than 12 spines), contiguous to the second. 

 d. Caudal keel present. 

 e. Corselet imperfect or obsolete ; teeth of jaws strong ; minute teeth ou 



vomer and palatines SCOMBEROMORUS, 215. 



ee. Corselet developed. 



/. Palatine teeth strong; vomer toothless; vertebrae normal. ..SARD A, 216. 

 ff. Palatine teeth villifonn. 



g. Vomer with teeth; vertebrae normal, the lower foramina small. 



ORCYNUS, 217. 



gg. Voiner toothless; abdominal vertebras with the lower foramina en- 

 larged and a portion between the vertebrae proper and the hsernapophy- 

 ses developed in the form of a net-work or trellis EUTHYNNUS, 218. 



213. SCOMBER Liuiiaeus. 



Mackerels. 



(Linnaeus, Syst. Nat. 1758: type Scomber sconibrus L.) 



Body fusiform, rather elongate, somewhat compressed; caudal pe- 

 duncle slender, with two small keels on each side. Mouth wide, with 

 a single row of rather small, slender teeth in each jaw and on the voiner 

 and palatines; maxillary slipping under the broad preorbital. Scales 

 very small, not forming a corselet. First dorsal of 7-12 feeble spines, 

 separated from the second by an interspace greater than the base of the 

 fin; second dorsal small, followed by 5-9 detached finlets; anal similar 

 to second dorsal, with similar fiulets ; pectorals and ventrals small, the 



