Jordan and Evermann. Fishes of North America. 121 



i. Spines Ions, scarcely shorter than head ; caudal nearly as long 



as head ; head small, 4 in length ; mouth small, its breadth 



not % head. OSCULU8, 184. 



mm. Spines short, not % head ; head large, about 3% in length; 



teeth on palate in 4 patches, bluntly conical; occipital 



process scarcely as long as broad; caudal shortish; 



mouth large, its breadth at least % length of head. 



EI.ATTURUB, 185. 



re. Palatine patches of teeth without a backward projecting angle on the inner margin; 



dorsal shield small, crescent-shaped ; general color brown with blue reflections. 

 Hi-XANEMATiciiTHYS, (ef, six ; i/jj/KU, thread ; i\6v<;, fish): (genus 73.) Species 186 to 196. 

 w. Teeth on palate villiform. 



o. Teeth on palate mostly in 4 patches. 



p. Granulations of head not extending forward to between eyes. 

 q. Fontanelle continued backward as a narrow groove. 



r. Occipital process long, about % head, its tip convex ; inner edge 



of ventrals pale ; head 3% in length. FEMS, 186. 



rr. Occipital process moderate, not % head ; inner edge of ventrals 



black ; head longer. 



s. Head flat, depressed in front ; occipital keel bluntish ; granu- 

 lations of head coarse and conspicuous ; fontanello reach- 

 ing base of occipital process. SEEMANI, 187. 

 ss. Head scarcely depressed ; occipital keel sharper than in any 

 other species ; shields of head smoother than in H. seemani; 

 patches of palatine teeth much smaller, fontanelle nar- 

 row, not quite reaching occipital keel. JORDANI, 188. 

 qq. Fontanelle not continued backward as a groove into the granulated 



region of the head. 



t. Palatine patches of teeth small, scarcely larger than vomerine 



patches, which are widely separated ; occipital process keeled, 



truncate at tip ; barbels rather long ; vertical fins dark ; inside 



of ventrals dusky. CJERULESCENS, 189. 



U. Palatine patches much larger than vomerine. 



11. Fontanelle almost obsolete, ending between eyes, not pro- 

 longed backward as a groove ; body slender, caudal about 

 as long as head ; paired fins pale. GUATEMALENSIS, 190. 

 UH. Fontanel.t ending midway between tip of snout and middle 

 of dorsal plate ; head broader than in preceding. 



ASSIMILIS, 191. 



pp. Granulations of head continued forward to between the eyes ; fontanelle 

 continued as a groove to base of occipital process ; interorbital area 

 with 4 granular ridges. 



v. Head moderate, 4% in length ; dorsal spine 1% in head ; highest anal 



ray less than 2 in head. DASYCEPHALUS, 193. 



rr. Head long, 3| in length ; dorsal spine 1% in head ; highest anal ray 



2% in head. LONGICEPHAMTS, 194. 



TAniYSCRtJS : (genus 74.) 



nn. Teeth on palate granular ; gill membranes not forming a free margin across the 



isthmus. 

 if. Anal rays 19 to 22 ; head broader than high, more than 3 in length. 



x. Ventral fins blackish on inner margin ; axillary pore large ; groove of fon- 

 tanelle scarcely reaching base of occipital process ; vomerine teeth 

 small, the patches widely separated ; head 3}^ in length. 



MELANOPUS, 200. 



xx. Ventral fins pale; axillary pore small; pectoral spino reaching at least 



halfway to middle of ventral ; occipital process little narrowed 



behind ; vomerine teeth course, the patches close together; head 3% 



in length. Fl'RTin, 201. 



ww. Anal rays 27 ; teeth on palate in 2 small bands widely separated ; fontanelle 



long and narrow ; head rough. MULTIRADIATUS, 202. 



