80 



MEMOIRS OF THE CARNEGIE MUSEUM. 



base of anal about equal to length of caudal peduncle plus the middle caudal rays; 

 the interhsemals, nine to thirteen in number, occupy four-tenths to six-tenths of 

 the distance between the base of the last anal ray and the caudal, beginning a 

 httle behind the tip of the last anal ray. Those of the male without lateral proc- 

 esses, sometimes with a low ridge or keel running along the sides of the anterior 

 ones and ending in a knob in front of them; lower caudal fulcra prominent, con- 

 tinuous with the interhsemals. Scales normal. 



There is a caudal spot of varying size and intensity, sometimes extending 



a ¥ 



Fig. 28. Cheirodon piaba Liitken. a, region between anal and caudal in 9 ; 6, Do. in (f. Lagoa 

 Paranagua, 6823, C. M. ; c, anal fin and caudal fulcra and interhsemals of (f , 6828, CM.; d, skeleton of fulcra and 

 interhsemals of cf , 6843, C. M. (All figures greatly enlarged.) 



entirely across the end of the caudal peduncle, sometimes extending on the middle 

 caudal rays, rarely to their tips; a faint black line overlaid with silvery along the 

 middle of the sides; anterior margin of dorsal dark; general color very pale or 

 quite dark, depending on the nature of the locality from which the specimens came. 

 It is possible that we should refer to this species a small specimen, 6909, C. M., 

 15 mm. long, taken in a tributary of the Guapore about forty miles south of Villa 

 de Matto Grosso. 



44. Cheirodon microdon sp. nov. (Plate XIV, fig. 1.) 

 This species is allied to Cheirodon stenodon and to Aphiocheirodon hemigrammus. 

 6850, C. M. Type, 42 mm. 6851a-b, C. M., paratypes two, the larger 41 mm., 

 Caceres, Upper Paraguay, May 24, 1909. Haseman. 



