Jordan and Evcrmann. — Fishes of North America. 121 



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



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



not J4 head. oscums, 1X4. 



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 y^ length of head. 



ELATTIUI'8, IS.'i. 

 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. 

 IIexanematichthys, (ef, six ; )/))/i.a, thread : ixCus, fish): (genus 73.) Species 186 to 19fi. 

 11. Teeth on palate villiform. 



o. Teeth on palate mostly in 4 patches. 



J), (ilrauulations of head not extending forward to between eyes. 

 (/. Fontanelle continued backward as a narrow groove. 



r. Occipital process long, about J.j he.ad, its tip convex ; inner edge 

 of ventrals pale ; head 354 '" length. fei.i.s, 186. 



rr. Occipital process modei-ate, not 3^ head ; inner edge of ventrals 

 black ; head longer, 

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

 lations of head coarse and conspicuous ; fontanelle reach- 

 ing base of occipital process. seemani, 187. 

 s-s. Head scarcely depressed ; occipital keel sharper than in any 

 otherspecies ; shields of head smoother than in IT.seemaui; 

 patches of palatine teeth much smaller, fontanelle nar- 

 row, not quite reaching occipital keel. .tordani, 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 

 jiatches, which are widely separated ; occipital process keeled, 

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

 of ventrals dusky. c.f.kule.scen.s, 189. 

 It. Palatine patches much larger than vomerine. 



»(. Fontanelle almost obsolete, ending between eyes, not pro- 

 longed backward as a groove ; body slender, caudal aliout 

 as long as head ; paired fins pale. odatemalensis, TOO. 

 "". 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. 

 II. Head moderate, i}/im length ; dorsal spine IJ^ in head ; highest anal 

 ray less than 2 in head. dasycephah's, 193. 



vv. Head long, 3| in length ; dors,al spine 1^4 in head ; highest anal ray 

 23^ in head. i.onoicephai.cs, 194. 



Taohysurtjs : (genus 74.) 

 ^nt. Teeth on palate granular ; gill membranes not forming a free margin acro.ss the 

 isthmus. 

 11'. Anal r.aj's 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 p.atches widely separated ; head Z\^, in length. 



MELANOrUS, 200. 



rx. Ventral fins pale ; axillary pore small; pectoral spine reaching at least 



halfway to middle of ventral ; occipital process little narrowed 



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



in length. fvrthi, 201. 



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



long and narrow ; head rough. multiradiatcs, 202. 



