30. CATOSTOMIDJE - ICTIOBUS. 113 



** Dorsal fin short, -with 10-18 rays. (Catostomince.) 

 e. Air-bladder in two parts. 

 /. Lateral Hue complete and continuous ; scales small, 55-115 in the 



lateral line. 

 q. Fontanelle none ............................... PANTOSTEUS, 63. 



gg. Fontanelle present. 



h. Mouth inferior, small, with thick papillose lips. 



CATOSTOMUS, 64. 



Mi. Mouth very large, terminal, oblique ; lips thin and nearly smooth. 

 t. Pharyugeal bones moderate, with teeth of medium size. 



CHASMISTES, 65. 



ii. Pharyngeal bones slender, with very numerous, minute teeth. 



LIPOMYZON, 66. 

 ff. Lateral line interrupted or wanting; scales large (40-50 in a longi- 



tudinal series). 

 g. Lateral line entirely wanting ..................... ERIMYZON, 67. 



gg. Lateral line more or less developed .............. MINYTREMA, 68. 



ee. Air-bladder in three parts ; fontanelle present ; scales large ; lateral 



line complete. 

 j. Mouth normal, the lower lip entire or merely lobed. 



A;. Pharyngeal bones moderate, the teeth compressed, grad- 

 ually larger downwards; mouth moderate or small, the 

 lips usually plicate ...................... MOXOSTOMA, 69. 



fcfc. Pharyngeal bones very strong, with the lower teeth much 

 enlarged, subcylindrical and truncate, the teeth of the 

 upper part of the bone small and compressed ; mouth large, 

 somewhat oblique, with very thick lips. 



PLACOPHARYNX, 70. 



jj. Mouth singular, the upper lip not protractile, greatly en- 

 larged, the lower lip developed as two separate lobes, 

 pharyugeal bones and teeth ordinary ---- QUASSILABIA, 71. 



59. ICTIEIJ Eafinesque. 



Buffalo-fishes. 



(Rafinesque, Ichth. Oh. 1820, 55: type Amblodon "biibalm Eaf.) 



Head very large and strong, wide and deep ; its length 3-3f in that 

 of the body ; its upper surface broad and depressed. Eye moderate, 

 wholly anterior in position, the middle of the head being entirely behind 

 it; suborbital bones proportionately harrow. Fontanelle large, well 

 open. Opercular apparatus largely developed; the suboperculum 

 broad ; the operculum broad, strongly furrowed. Mouth very large for a 

 sucker, terminal, protractile forwards; the middle of the premaxillaries 

 nearly on the line ot the middle of the eye ; the posterior edge of the maxil- 

 lary extending about to the line of the nostrils. Mandible very strong, 

 oblique, placed at an angle of 45 or more when the mouth is closed, its 

 posterior end extending to beyond opposite the front of the eye, its 

 length a little less than one-third that of the head. Lips very little de- 

 veloped ; the upper narrow and smooth, scarcely appreciable ; the lower 

 narrow, rather full on the sides, but reduced to a narrow rim in front, 

 Bull. Nat. Mus. No. 1G - 8 



