104 Annals of the Carnegie Museum. 



Ctenohrycon spilurus (Cuvier & Valenciennes). Scales transversely 

 long-oval or oblong, about one and one-third mm. long and two mm. 

 broad; nucleus a short distance basad of the middle; radii two, in 

 the form of a V, or one, or none; the whole scale covered with 

 circuli, which are widely spaced except basally, the apical ones 

 practically transverse, but forming a very open angle where they 

 meet in the middle line. A very distinct type of scale, wholly unlike 

 those of Creatochanes, etc. 



Ctenohrycon haiixwellianns (Cope). Collected by William James at 

 lea (Thayer Expedition). Scales thin, transverse, about two mm. 

 long and two and one-half mm. broad, with rounded laterobasal 

 corners; basal and lateral circuli ordinary, but quite widely spaced; 

 apical circuli transverse, but more or less broken, and in the sub- 

 marginal area thrown into waves, which become strong on the 

 margin, producing an irregular series of short marginal teeth (of 

 the general type of those in Citharidium, but less developed) a 

 few feeble, irregularly placed apical radii. This, the type of 

 Ctenohrycon, has scales which differ considerably from those of C. 

 spiluriis; the latter should probably be separated gcnerically or 

 subgenerically, in which case it falls into the subgenus Pccciln- 



richthys. 



Ilemigrammiis Gill. 



The small thin scales of this genus are very uniform, and are of the 

 form shown in Plate XXVII, fig. 2, representing //. orthus Durbin, 

 from a drawing by Miss Evelyn Moore. It will be seen at once that 

 this is the Cheirodon type of scale, and has no resemblance to Cteno- 

 hrycon, and not very much to Creatochanes, although agreeing in the 

 absence of circuli in the apical field. 

 Hemigrammus rodwayi Durbin. Scales three mm. broad; apical 



radii strong, very variable, from three to twelve; nuclear area 



pustulose in appearance. 

 Hemigrammus analis Durbin. Scales about one and one-third mm. 



broad; radii about two to four; nuclear sculpture as in //. rodwayi. 

 IlemigramniHs orthus Durbin (Plate XX\TI, fig. 2). Scales about or 



hardly one mm. broad; radii two, rareh" four; nuclear sculpture as 



in //. analis, but less distinct. 

 Hemigrammus cylindriciis Durbin. Scales about one and two-thirds 



mm. broad, much rounder than in the other species; radii usually 



two, sometimes four; nuclear sculjJture distinct. The form of the 



