156 CALIFORNIA ACADEMY OF SCIENCKS. 



Localities: Pernambuco; Saa GouQallo; Eio Sau Francisco, below 

 tlie Falls; Tabatinga; Teife; Rio Puty. ' 



170. Trachycorystes robustus Giiutber. 



171. Trachycorystes analis sp. nov. 



Type, No. 7354, one specimen; length, .21 m. Arary ? Professor 

 Agassiz. 



Width of the head equal to its length; width of the 

 mouth If in length of head; the depth at the occipital 

 process 1:^ in the length of the head. Fontanel oval, 

 surrounded by bone. 



Mental barbels less than one-third the length of the 

 head. 



Dorsal spine I5 in head, its anterior margin smooth 

 except near the tip, its^posterior margin slightly serrate. 



Caudal broken. 



Anal rays crowded, gradually decreasing in height back- 

 ward, the margin undulating. 



Pectoral spine very strong, 3| in the length. 



Dark brown; ventral surface dusky with numerous dark 

 points; dorsal fin with dark spots most prominent near the 

 free margin; tips of ventrals dusky, the base profusely 

 dotted, the intermediate region almost plain yellowish; 

 pectoral fin profusely spotted. 



Head 4; depth, 4f ; D. I, 6; A. 41; Y. 6: P. I, 7. 



Otherwise as in mactdosus. 



XXXVII. Centromochlus Kner. 

 ''!/ Centromochlus. 



172. ? Arius oncina Schomburgk. 



173. Centromochlus heckelii (Filippi.) 



Centromuchlus megalops Kner. 



Localities: Villa Bella; Obidos; Para; Tabatinga; Guru pa; Manaoa*^ 

 puru; Lago Alexo; Hyavary. 



174. Centromochlus steindachneri Gill. 



175. Centromochlus intermedius steindachner. 



Localities: Tajapuru; Teflfe; Jatiiarana; Iq&; Jutahy; Lago Alexo. 



