130 Bulletin 4J, United States National Museum. 



pectorals. Opercle smooth. Dorsal spine shorter than the pectoral spine, 

 ahout 2 in the head, granulated in front, striated on sides; caudal 4 in 

 length Surinam. (Bleeker). 



Uexanemalichthyf siirinarnensis, Bleeker, Vcrsl. Med. Akad. Wet. Amsterd., 380, 1802, Surinam. 



Arius surinametisk, GCnthek, Cat., v, 148, 1864. 



Tachistirus surinmensis, Eioenmanm, S. A. Nenjatoguathi, 81,1890. 



193. HEX.4NEMATK'HTHYS DASICEPHALUS, (GUnther). 



Head 44. A. 21. Interorbitalarea with 4 very rough granulated ridges; 

 (smoother in 9); shieldsof head coarsely granular; vomerine and palatine 

 teeth on each side confluent in a small roundish patch; gill membranes 

 not forming an angle ; fontanelle continued backward as a groove to base 

 of occipital process; spines high; the dorsal li in head. Fins blackish. 

 Panama (wrongly ascribed to the Hawaiian Islands). ((S«arf, rough; 

 KE(^a7^7], head.) 



Arius dasycephalus, GfNTHER, Cat., v, 1864, 157, Oahu, appareutly an error. 

 Arius dasycephalus, Jordan & Gilbert, I. c, 51, 1882. 



194. HEXAXE.MATICHTHIS LONGICEPHALUS, Eigenmann & Eigennianu. 



Head 3.?. A. 20. Allied to II. dasycephalus, but with the granular ridges 

 on the head largely obscured by thick skin; occipital process as long 

 as broad, its margins concave; fontanelle produced as a deep groove; 

 barbels short; gill rakers short and thick, 4 + 5; spinesshort; finsdusky. 

 Panama. (Eigenmann.) (longiis, long; Ke<pa?ir/, head.) 



Tachixnnis lowjicephalus, EIGENMANN & Eigenmann, Proc. Cal. Ac. Sci., 1888, 143, Panama ; 

 Eigenmann, S. A. Nematognathi, 82, 1890. 



195. HEXANEMATICHTHTS RUGISPINIS, (Cuvier & Valenciennes). 



Head 34 to 4 ; depth 5i to 6. D. I, 7 ; A. 19 to 21. Palatine bands of 

 teeth not continued backward; teeth all villiform. Teeth on the palate 

 in 2 patches. Eye small, about 10 in the length of the head; fontanelle 

 not continued as a groove. Sides of the dorsal and pectoral spines gran- 

 ular; fontanelle angular behind, its posterior portion separated by a 

 bridge and not ending in a groove; interorbital region with 4 ridges; 

 intermaxillary band of teeth 4 times as wide as deep; palatine patches 

 of teeth less than diameter of eye in width. Barbels villiform, the max- 

 illary barbel reaching beyond base of pectoral; mouth inferior, the lips 

 thick; no axillary pore. Body slender; head broad, depressed. Surinam 

 to Para. (Eigenmann.) (ruga, Avrinkle or roughness; sjjina, spine.) 



Arius riigispinvi, Cuvier A Valenciennes, xv, 77, 1840, Cayenne. 



Arius rugispiuis, GOnther, Cat., v, 156,1864. 



Tachisurus rugispinis, Eigenmann, S. A. Nematognathi, fi3, 1890. 



196. HEXAXEMATICHTHYS PHRTGIATIS, (Cuvier & Valenciennes). 



This species or variety is very close to H. rugispiuis, differing as follows: 

 Teeth on the palate in 2 patches. Eye small, about 10 in the length of 

 the head; fontanelle not continued as a groove. Sides of the dorsal and 

 pectoral spines striate; fontanelle broadly rounded behind; intermaxillary 



