212 CALIFORNIA ACADEMY OF SCIENCES. 



based on specimens 1.50 and .50 m. long respectively, 

 and little value can be laid on their differences. 



The specimens examined are from Rio das Velhas, 

 and Rio San Francisco below the falls. 



Body long, slender, terete, head very long, more de- 

 pressed than in other species; maxillary barbel extending 

 beyond preopercle; mental barbels to pectoral or shorter; 

 postmental barbels almost to tip of pectoral; width of 

 head at rictus scarcely narrower than its greatest width; 

 2^ in its length; greatest depth of head 4 in its length. 



Eye 13 in head, 6 in snout, 3| in interorbital, 3| 

 diameters from angle of mouth. 



Teeth all alike, arranged as in fasciatum. 



Gill-membranes separate to beyond eye; gill-rakers 

 short, spine-like, not overlapping, l-|-8. 



Dorsal spine nearer posterior margin of adipose dor- 

 sal than to tip of snout. 



Adipose fin shorter than base of anal. 



Caudal deeply two-lobed, the outer rays 4 times as 

 wide as an interradial space, the lobes rounded. 



Ventrals extending h their length behind vent. Dis- 

 tance from vent to anal about equal to 6 diameters of 

 the eye, from vent to the caudal | longer than the head. 



Pectoral spine finely serrate behind, 2-J- in head; pec- 

 toral pore minute. 



Head 2|; depth 7; Br. 15 or 16; D. I, 6; A. 14. 



XXXVI. SORUBIM. 



Platystoma Agassiz, Gen. et Spec. Pis. Bras. 1829 (sp.) 

 (name preoccupied in Diptera). 



Sorubim Spix, Gen. et Spec. Pise. Bras. 1829 (sp.) 



Sorubivi Bleeker, Nederl. Tijdschr. Dierkunde,i, 1862, 

 Systema Sil. Rev. 22 (lima). 



Tpye: Siluinis lima Bloch & Schneider, 



Neither Agassiz nor Spix indicated types for their gen^ 



