22 Mr. C. T. Regan on the 



usually compressed, often cuspidate ; palate toothless. 

 Hyoraandibular with a single head fitting into a groove ; 

 pterygoid normally attached to quadrate. Orbitosphenoid 

 iformius a long sutural union with frontals. Dorsal fin 

 median, often rather elongate ; scales usually ciliated ; lateral 

 line, wlien present, straight. 



This very natural group of African fishes corresponds to 

 the Ichtliyoborinae, Disticliodontinse, and Citharininse of 

 Boulenger, after excluding from the latter the American 

 genera Curimatus and Prochilodus. 



In the following arrangement of the genera important 

 differences in the structure of the lower jaw are for the first 

 time taken into account : — ^ 



I. Kami of lower jaw widely separated for the greater part of their 



length, anteriorly slender and curved together, movahly connected 

 at the symphysis ; dentary and articulare firmly united *. 



Scales strongly ciliated ; maxillary rather 

 large, movably articulated with prajmax- 

 illary ; upper jaw not or scarcely pro- 

 jecting beyond the lower; teeth small, 

 bicuspid, in 2 or 3 series. {Xenochai-a- 



cince.) Nanyicetkiops, Neokhias, 



Xenocharax. 



Scales strongly ciliated ; maxillary united 

 with pra?maxiUary ; upper jaw strongly 

 projecting, toothless anteriorly; teeth 

 very small, bicuspid, uniserial. {Hemi- 

 stichodo7itmce.) Hemistichodus, 



Scales cycloid, or with the marginal teeth 

 few aud strong ; maxillary small, adhe- 

 rent to prsem axillary ; teeth minute, 

 pointed or truncate, uniserial, on the 

 labial margin. {CitharinincB.) Citharidium, Citharinus. 



II. Dentaries more or less massive, firmly connected at the symphysis, 



movably articulated with the articulares. 



A. Mouth small, subterminal or inferior ; lower jaw short, with the 



rather massive dentaries merely coalescent; maxillary well 

 developed, adherent to pra^maxillary ; teeth small, bicuspid, in 

 1 or 2 series. {Distichodonttncs.) . . Distichodus,Na}inocharax. 



B. Mouth terminal, rather large, the jaws produced; dentaries very 



massive, united by a long suture ; prasmaxillaries similar to the 

 dentaries, with the reduced maxillaries united to them by suture. 

 {^Ichthyobormce. ) 

 No canines ; teeth biserial, the outer strong, 

 compressed, bi- or tricuspid ; maxillary 



entering the gape Eugnathichthys, Para- 



phago, Phago, 



* I find a w«ll-dev eloped angulare in Citharinus, as in other Characi- 

 formes. 



