112 CALIFORNIA ACADEMY OF SCIENCES. 



partly lost, so an exact count is impossible. As already 

 stated, Dr. Steindachner's figures of P. brevis do not agree 

 with the specimens examined by us. The comparisons 

 made in the key are based on the specimens examined, 



7. Pyrrhulina nattereri. 



FijrrhuHaa natlererl Steiud '75a, 8, pi. ii, fig. 5-5a (mouth of Rio Ne- 

 gro; Obidos). 



Habitat: Amazous from Obidos to Cudajas. 



One hundred and sixty specimens, the largest .055 m. Rio Trom- 

 betas; Villa Bella; Manaos; Silva, Lake Sarac.i; Hyanuary; Cud- 

 ajas; Jatuaraua; Obidos. 



This is the most slender species of Pyrrhulina. It can 

 easily be recognized by the color. Each scale has a silvery 

 center and dusky margin. In some specimens the color 

 markings of the lower half of the sides are obliterated by a 

 dusky lateral band, the region above it being lighter than 

 usual. The fins vary greatly in height. In the largest 

 specimen the height of the dorsal is little less than half the 

 length, and the ventrals reach beyond the base of the anal. 

 Usually the dorsal does not reach to the caudal, and the 

 ventrals not to the anal. 



8. Pyrrhulina guttata. 



Pyrrhulina guttata Steind. 75a, 10, pi. ii, tig. 6-6a (Obidos; Cudajas; 



Tabatinga; Rio Negro). 

 Habitat: Amazous from CJurupa to Tabatinga, Kio Negro. 



The relative abundance of this species may be seen from 

 the number of specimens from each locality. 



Gurupa, 3 specimens; Tajapuru, 11; Villa Bella, 6; Obi- 

 dos, 399; Santarem, 1; Manacapuru, 24; Cudajas, 8; Tab- 

 atinga, 31; Curupira, 2. 



The largest specimen is from Cudajas, and measures .098 

 m. The color varies greatly, the markings are more constant. 

 The specimens from Cudajas are light straw colored; those 

 from Obidos dark brown, lighter below. There is usually 

 a silvery white spot at the base of each scale of the sides; 

 they are sometimes found on the median scales of the tail 



