Families of Teleostean Fishes. 1 1 * 



Suborder X. ACANTHOPTEBTGII, 

 Air-bladder usually without open duct. Opercle well deve- 

 loped ; supraoccipital in contact with the frontals. Pectoral 

 arch suspended from the skull ; no niesocoracoid. Ventral 

 fins thoracic or jugular, the pelvic bones more or less firmly- 

 attached to the clavicular arch. Gill-opening usually large ; 

 if small, in front of or above the base of the pectoral fin. 



The character from which this suborder, the most com- 

 prehensive of the whole class, derives its name, viz. the 

 presence of non-articulated, more or les3 pungent rays in 

 the dorsal and anal fins, is by no means universal, exceptions 

 to the rule being numerous. The mouth is usually bordered 

 by the premaxillaries to the exclusion of the maxillaries, and 

 if these should, by exception, enter the oral edge, they are 

 always toothless. The ventral fins are sometimes inserted 

 at some distance behind the base of the pectorals (Ilaplo- 

 dactylidse, Platycephalidse), in which case, however, this is 

 merely due to the elongation of the pelvic bones, which are 

 solidly attached to the clavicular arch. The suborder is 

 broken up into 9 divisions, which follow in somewhat ar- 

 bitrary order, the natural affinities being opposed to a linear 

 arrangement. 



I. Xo suborbital stay, or process extending from the suborbital bones 



towards the prseoperculum ; basis crauii double in the symmetrical 

 forms. Primary shoulder-girdle composed of a perforate scapula 

 and a coracoid ; of the four or five pterygials, or basal bones of 

 the pectoral fins, only one or two are in contact with the 

 coracoid ; ventral fins thoracic. 

 Kays cf the caudal fin not strongly forked at 



the base ; hypural usually with a basal 



spine or knob-like process on each side ; 



epipleural bones usually inserted on the 



parapophyses or on the ribs ; dorsal tin 



usually with strong spines ; caudal peduncle 



rarely much constricted I. PERCiFonuF.s. 



Rays of the caudal iin strongly forked at the 



base, embracing a considerable portion of 



the hypural, which always bears a basal 



spine ; epipleuial bones usually inserted on 



the centra or on the parapophyses, rarely 



on the ribs ; dorsal spines feeble or de- 

 tached; caudal peduucle much constricted; 



scales usually very small or absent IT. Scombriformes. 



Pays of the caudal fin not strongly forked at the 



base, no hypural spine, and ventral fins with 



one spiue and six to eight soft rays, or 



cranium asymmetrical III. Zeorhombt. 



II. No suborbital stay ; basis cranii double ; scapula absent, the 



pterygials inserted on the coracoid ; ventral fins thoracic. 



IV. KuttTIFORMES. 



Ann. & Mag. N. Hist. Ser. 7. Vol. xiii. 12 



