404 CALIFORNIA ACADEMY OF SCIENCES. 



strongly carinate; humeral keel strong, continued almost 

 to the caudal fin, the keel indistinct on the caudal portion 

 in the young. Tip of the snout naked. 



Eye 3J-5J in the snout, 6-9 in the head, 2J-3J in 

 the interorbital. 



Belly entirely covered with small scales. 



Base of the dorsal fin little longer than its distance 

 from the adipose fin; first ray of the dorsal much higher 

 than the last ray, about equal to the length of the head. 



Outer caudal rays little produced, the shortest ray 

 about 1J in the head. 



Sides, back and all the fins thickly covered with small 

 roundish dark spots; those on the caudal as conspicuous 

 as the spots on the dorsal fin; in one series between every 

 two rays on the caudal, in 2-6 series on the dorsal; ven- 

 tral surface plain in the adult. 



Lat. 1. 28-30. Head 3J-3J. 



Nineteen specimens .11-. 37 m. Rio de Janeiro; Santa 

 Cruz; Macacos; Itabapuana; Rio Parahyba. 



346a, Plecostomus commersonii affinis. 



? Plecosiomus punctatus Giinther, v, 233, 1864 (South America); not 



H. punctatus C. & V. 

 Plecostomus affinis Steindachner, Siisswasserfische Siidostl. Bras. 



iii, 127 (Bio Mucuri, near Santa Clara; Eio Parahyba; Muriahe; 



San Antonio, near San Antonio de Ferros). 

 Plecostomus commersonii affinis Eigenm. & Eigenm. Proc. Cal. Acad. 



2d Ser. i, 168, 1888 (Mendez; Santa Clara; Minas Geraes; Eio 



Doce at Linhares; Mucuri, Janeiro; Parahyba; San Antonio). 

 Habitat: Southeastern Brazil. 



This variety is much more common than commersonii 

 from which it differs by the much larger spots. The 

 keels of the head are almost obsolete in some of the 

 specimens. 



We have examined over fifty specimens from .13-. 26 

 in. long. 



Mendez; Santa Clara; Rio Mucuri; Rio de Janeiro; Rio 

 Doce at Linhares; Rio Parahyba; Minas Geraes; San An- 

 tonio River. 



