2 Memoir Sears Foundation for Marine Research 



Superclass PISCES 



Both the cartilaginous fishes (8) and the bony fishes have been grouped together 

 under the name Pisces by Goodrich (45) as a Grade intermediate between Branch and 

 Subgrade, by Berg (4) as a Series intermediate between Superclass and Class, and by 

 Bertin and Arambourg (jj) as a Superclass. This last arrangement, with Pisces ranked 

 as a Superclass, is accepted here to embrace both cartilaginous fishes (Chondrichthyes) 

 and bony fishes (Osteichthyes). The cyclostomes, not regarded here as fishes in the 

 usual sense, are considered a separate Branch (Agnatha) of the vertebrate Subphylum 

 Craniata. 



Bertin and Arambourg (jj: 1956) have expanded the Superclass Pisces to include 

 the fossil Placodermi (including the Acanthodii and the Athrodiri); this ancient group, 

 however, was only remotely related to either the living cartilaginous fishes or the 

 living bony fishes. See Romer (75: 38-59) for an account of the placoderms and 

 their evolutionary pattern. 



C/ass OSTEICHTHYES 



Characters of Living Members. The internal skeleton contains true bone in greater 

 or lesser amount, especially in the regions of the skull, the jaws, and the pectoral arch. In 

 most the jaws are well developed, but in a few they are greatly reduced. The palato- 

 pterygoid part of the upper jaw-complex is fused solidly with the lower surface of the 

 skull in the Dipnoi (lungfishes) but not in the others, with one exception {l^: 273). 

 The teeth are usually embedded in the bone (but see p. 6 for exceptions). In a few there 

 is a spiracular opening between the jaws and the hyoid arch (polypteroids and some 

 acipenseroids). The external opening of each nostril is typically double but is single in 

 a few (p. 6); the nasal sac ends blindly in most but opens internally into the mouth in 

 some. There is only one external gill opening on each side, and the two openings are 

 often united across the throat; the common chamber into which the internal gill clefts 

 open is roofed over by a dermal opercular flap supported in most cases by a series of 

 opercular bones. A typical bony fish has four or five pairs of gill arches (the fifth the 

 smallest) and four to six pairs of internal gill clefts.* 



The majority has two sets of paired fins — pelvic and pectoral. The pectoral girdle 

 is well developed and is attached at its upper end to the temporal region of the skull 

 in the great majority (see p. 6 for exceptions). The endoskeletal support of the pectoral 

 and pelvic fins consists ot either one or two series of short basal elements;^ in the typical 

 pectoral fin these elements are in parallel or fan-like arrangement (Actinopterygli in 

 general, p. 1 1), with the outer part of the fin supported by fin rays; but in some there 

 is a jointed midrib with either a series of short side branches on each side, as in the 

 Dipnoi, or a terminal fan of jointed rays (Fig. 2), as in the living coelacanth Latimeria 



1. According to Tchernavin {84: 284), there are six gill clefts in Eurypharynx (gulper eel). 



2. The basalia of the pectorals are fused in Daltia to form a single plate; in Lophius there are only two; and in 

 general they are much reduced in the pelvics. 



