THE ORDERS OF TELEOSTOMOUS FISHES 475 



Margin of upper (Characins) (Carps) (Catfishes) 



jaw Formed by pre- Formed by pre- Formed by pmx. 



max. and max. max. or by pre- alone ; mx. much 

 max. and max. reduced. 



Teeth on jaws . . . .Often present Absent Absent or limited 



to pmx. 

 Upper pharyn- 

 geals 1-4 •. 2 ? Normal. 



Lower pharyn- 

 geals Normal, toothless. Falciform, toothed. Normal. 



Opercular appara- 

 tus Normal, complete. Normal, complete. Lacking suboper- 



culum and some- 

 times operculum. 



Brain case Not ossified later- Ossified laterally Ossified laterally 



ally between between orbits. between orbits, 

 orbits. 



Parietals Distinct from su- Distinct from su- Usually fused with 



praoccipital. praoccipital. the supra occipi- 



tal which is great- 

 ly developed. 



Adipose dorsal — Often present Absent Often present. 



' ' Interclavicles ' ' . Absent Absent Present. 



Parapophyses on 

 precaudal 



vertebrae Absent Absent Often present. 



Pyloric caeca Often present Absent .....? 



Order Ostariophysi (cont'd) . 

 Suborder Nematognathi 1 Gill 

 The Catfishes. 

 The name Nematognathi refers to the reduction of the maxil- 

 lary to a slender element bearing the thread-like barbels; the 

 premaxillaries alone forming the margin of the upper jaw. 2 

 Barbels are always present ; the premaxillaries are not protractile, 

 jaw-teeth if present are limited to the premaxillaries; the skull 

 (as in Carps) is closed at the side by the orbitosphenoids and 

 ethmoid; the supraoccipital is greatly developed, and usually 

 fused with the parietals; an adipose dorsal fin is often present. 

 The Catfishes show certain resemblances to the Acipenseroidei, 

 in that: (1) the skin is naked, or armed with either bony 

 scutes or plates; (2) the suboperculum is absent; (3) certain 

 forms (Doras) exhibit fulcra-like scutes on the anterior border 

 of the median fins; (4) the clavicles are braced inferiorlyjby 

 infraclavicular plates. The latter, however, are not generally 



1 vrjua, thread, yva'Qo?, jaw. 



2 Except in Diplomystes (Eigenmann.) 



