522 PROCEEDINGS OF THE ACADEMY OF [Julv, 



70. Poecilurichthys dichrourus Kner. 



Six specimens (No. 7 in part), Asuncion, Rio Paraguay. November, 

 1899. "Edible; taken in a fish trap; commonly called Piki." 



Two specimens (251 in part), creek near Arroyo Trementina. 



These specimens are slenderer than Kner's figure. There is a 

 faint caudal spot. The middle caudal rays and the distal half of each 

 caudal lobe black. Maxillary ^Yith one or two small teeth. 



The following table shows the measurements of the eight specimens : 



Min. Max. Average. 



Length in mm 34.0 48.0 41.1 



Anal 24 28 



Depth 3.0 3.75 



Head 3.5 4.0 



Eye 2.4 2.6 



Scales 5.5 to 5.5-34 to 39-4.5 to 5. 



71. Poecilurichtliys agassizii Steindachner. 



Four specimens, Arroyo Trementina (240) ; Arroyo Chagalalina (229). 

 Head 3^-3^; depth 2|-2i; eye 2|-2f in the head; A. 24-26; Lat. 

 1., 25. 



72. Poecilurichthys moenkhausii sp. nov. 



Type No. 10,001, a specimen 43 mm. (251 in part), a brook near 

 Arroyo Trementina. 



Co-type No. 10,002, one specimen (251 in part), taken with the 

 type. 



Co-types No. 10,003, nine specimens (255), a brook near Arroyo 

 Trementina. 



This species is related to Tetragonopterus pauckh^is, from which it 

 differs in the depth, the greater number of scales and absence of caudal 

 spot. 



A symmetrical, elongate species. Depth 3h. Snout blunt. The 

 dorsal and ventral profiles of the head alike. Body deepest just 

 before the ventrals, tapering gently both above and below to the cau- 

 dal. Scales moderate. Lateral line complete. 



Head short, 4 in the length, its depth 1^ in its length. The oper- 

 cle narrow, its width more than 2 in its depth. The maxillary moder- 

 ately long, extending to beneath the anterior rim of the orlDit, two small 

 teeth in its upper end. 



The eye moderately large, 3 in the head, 1 in the interorbital. 



Dorsal rays 9. Height of dorsal slightly less than the length of the 

 head. The origin of the dorsal falls just back of the insertion of the 

 ventrals. 



