Fishes of the JVestern North Atlantic 3 



(jj: 2567, 2570, fig. 1840). The marginal parts of both the single and paired fins 

 are supported, at least in part, by jointed (segmented) and usually branched rays which 

 are either bony or fibrous in composition; in some the rays are apparently single,^ 

 but in the great majority each ray consists of a right-hand and left-hand half, the halves 

 closely pressed together (Fig. i). In a great majority the dorsal, caudal, and anal fins 

 are separated, one from the next, but in some these fins are continuous around the tip 

 of the tail. 



In a great majority the scales are wholly of mesodermic origin and are embedded 

 in the skin below the epidermis. The outer surface of the scales consists of a simple 

 calcified layer in most but of an enamel-like substance (ganoine) in a few. In most the 

 scales persist throughout life and grow as the fish grows, generally without increase 

 in number or modification except as they may be replaced when accidentally lost. How- 

 ever, in some of the goby-like fishes, additional scales are normally interpolated with 

 growth* in the region of the caudal peduncle. 



The anal, genital, and urinary tracts open separately to the exterior in most but 

 into a common cloacal pouch in a few. Some of the members of most of the major 

 groups have a swim bladder developed as a diverticulum from the dorsal side of either 

 the oesophagus or the stomach; a few (Dipnoi, polypteroids) have a functional lung (or 

 lungs) developed as an outpocketing from the ventral side of the pharynx.^ 



The notochord is persistent and unconstricted from end to end in a few, but in 

 most it is sharply constricted in its passage through the vertebral centra, often to thread- 

 like proportions, if it is not obliterated altogether. 



Nomenclature.^ The name Osteichthyes, proposed by Howes (3.^: 78, 87), has been 

 adopted by Goodrich (^5: 210) and by numerous subsequent students, including Berg 

 (j: xv), Goodrich,' Romer (7J: 75), Schultz and Stern (^yy : 227), Matsubara (.^7: 

 78, 154), and Bertin and Arambourg (ji": 1978, 2068). It is equivalent to the Class 

 Pisces of Linnaeus (^6), except that Linnaeus excluded the genera Acipenser (sturgeons) 

 and Lophius (anglerfishes) ; it is also equivalent to the Subclasses Lophobranchii plus 

 Potomabranchii of Bonaparte (jo: add. 13), with the addition of the lungfishes, which 

 were unknown to Bonaparte;* it also equals: the combined Subclasses Dipnoi, Teleostei, 

 and Ganoidei of Miiller (5j: 201-204); the Class Pisces as restricted by Jordan 

 (jp: 108) and by Regan {ji [1929]: 305); the Teleostomi of Stensio;^ the Classes 



3. The situation in this respect is not known for either the coelacanths or the Dipnoi. 



4. Steindachner and Doderlein [8i: 269) have reported this for Cepola; Koumans (^j: 267-279) has described in detail 

 and pictured clearly a similar situation for Oxyeleotris. Furthermore, J. R. Dymond (personal communication) 

 states that he has found in salmon and trout "... .what appear to be rows or partial rows [of scales] that appear 

 to have been developed later than the rows above and below"; and Hubbs (j6: 82) has reported an increase, 

 caused by parasites, in the number of scales in the genus Platygobius. 



5. Millet and Anthony (jjr: 2584) have reported a vestigial lung ("poumon degenere") of large size in the living 

 coelacanth Latimeria. For a general survey of the relation between swim bladder and lung of living fishes, see Romer 



(J4- 344-345. 347-35°)- 



6. See Myers (54: 31-40) for nomenclature of terms that have been used for the higher categories of fishes. 



7. Ref. (jo: xvii); considered a Subgrade of Class Pisces. 



8. Ref. {10: i6)j name Dipnoa used for Amphibia. 



9. Ref. [82: III); taxonomic rank not stated. 



