126 Bulletin <//, United States National Museum. 



Silurus parkeri, TRAILL, Mem. Werner. Soc., 1832, vi, 377, pi. G, Guiana. 



Arius parkeri, G(JNTIIER, Cat., v, 153, 1864. 



Tachisurus parkeri, EiGENMANN, S. A. Nematognathi, 65, 1890. 



Arius quadriscutis, CUVIER & VALENCIENNES, xv, 111, 1840, Cayenne ; Mana. 



Netuma quadriscutis, BLEEKER, Silures de Suriname, 59, 1864, with plates. 



72. NETUMA, Bleeker. 



177. NETUMA GRANDICASSIS, (Cuvier & Valenciennee). 



Head 3 to 3|; depth 5f to 6. D. I, 7; A. 18. Dorsal plates cresent- 

 shaped, not enlarged. Occipital process shaped like a clover leaflet, 

 emarginate at tip, narrowly and deeply constricted at base, its margins 

 regularly and strongly convex ; its middle keeled or not ; its length not 

 much greater than its breadth. Body cylindrical in front, tapering 

 behind. Head greatly depressed, longer than broad; center of fontanelle 

 over middle of eye, not continued backward as a groove; interorbital 

 region with 4 ridges; upper jaw considerably projecting; lip wide; vome- 

 rine teeth in small patches or wanting; palatine patches triangular, pro- 

 duced backward. Guiana to Bahia. (Eigenrnanu.) (grandis, large; cassis, 

 helmet.) 



Arius grandicassis, CUVIER & VALENCIENNES, xv, 53, pi. 427, 1840, Guiana ? 



Arius grandicassis, GVNTHER, Cat., v, 153, 1864. 



Tachisurus grandicassis, EIGENMANN, S. A. Nematognathi, 65, 1890. 



178. NETUMA STRICTICASS.IS, (Cuvier & Valenciennes). 



Entirely similar to N. grandicassis, but with the occipital process much 

 narrowed, its margins scarcely convex, and its length 2 or 3 times its great- 

 est breadth. The form of this process varies, so that Eigenmann regards 

 this form as a variety of N. grandicassis, another subspecies (parmocassis, 

 Cuvier & Valenciennes, from Bahia), being intermediate between the two. 

 Surinam to Bahia. (Eigenmann.) (strictus, narrowed; cassis, helmet.) 



Arius stricticassis, CUVIER & VALENCIENNES, xv, 58, 1840, Cayenne. 



Arius stricticassis, GUNTHER, Cat., v, 154, 1864. 



Tachisurus grandicassis stricticassis, EIGENMANN, S. A. Nematognathi, 68, 1890. 



179. NETUMA DUBIA, (Bleeker). 



Head 41 to 4 in length ; eye 4 to 4| in head, H to If in interocular space ; 

 body little broader than high; caudal compressed ; head depressed, acute, 

 its width 1J to 1 in its length ; width of mouth 2i to 2. D. 1, 7 ; A. 18 to 

 20. Dorsal plate, crescent shaped, not enlarged. Palatine bauds of teeth 

 without backward extension . Teeth villiform. Occipital process widest at 

 its base. Interorbital region granular, or if smooth, the fontauelle with- 

 out a groove. Posterior nasal openings not connected by a membrane. 

 Fontanelle not produced backward as a groove. . Maxillary barbels reach- 

 ing to base of ventrals. Occipital process keeled, not much longer than 

 broad; snout scarcely longer than eye, depressed, a large axillary pore; 

 dorsal spine li in head, granulated on its basal half in front, striate on 

 sides, slightly serrate behind ; adipose longer than dorsal fin, twice as 

 long as high ; pectoral spine broader but not longer than dorsal spine, its 

 inner margin conspicuously serrated ; ventrals much shorter than pecto- 

 rals ; anal as high as long ; caudal 4| to 6 in the length. Surinam. 

 (Bleeker.) (dubius, doubtful.) 



