200 CALIFORNIA ACADEMY OF SCIENCES. 



Head 3f; depth 5|-6; Br. 12 or 13; D. I, 6; A. 15. 

 Two specimens, from Para. 



XXXI. DUOPALATINUS. 



Duopalatinus Eigenm. & Eigenm. Proc. Cal. Acad. 2d 

 Ser. i, 136, 1888 (emarginatus). 



Type: Platystoma emarginatum Cuv. & Val. 



Teeth all alike, the vomerine patches far removed from 

 the palatine patches. 



This genus is closely related to Brachyplatystoma from 

 which it differs in the nature and position of the teeth. 



146. Duopalatinus emarginatus. 



Platystoma emarginatum Cuv. & Val. Hist. Nat. Poiss. xv, 25, 1840 

 (San Francisco); Liitken, Dan. Selsk. Skr. 1875, 152, fig. (Kio 

 das Velhas). 



Duopalatinus emarginatus Eigenm. & Eigenm. Proc. Cal. Acad. 2d 

 Ser. i, 1888 (Eio das Velhas; Eio San Francisco below the falls). 



Habitat: Eio San Francisco and its tributaries. 



This species being the sole representative of the genus 

 can most readily be distinguished by its teeth. 



Head narrow, little depressed; width at angle of mouth 

 1J in greatest width, 2 in its length; its greatest depth 

 2J in its length; upper jaw scarcely projecting. 



Maxillary barbel reaching to anal; mental barbel ex- 

 tending to base of pectoral, the postmental to tip of pec- 

 toral. 



Teeth of the upper jaw 

 in a band which is not 

 much narrower at the mid- 

 dle; vomerine teeth, in 

 the young, in two small /) 

 ovate patches distinct \J 

 from each other; in much larger 

 united patches in adult; palatine 

 patches ovate, removed from the vo- 

 merine patches. 



