30. CATOSTOMIDiE ICTIOBUS. 
113 
Dorsal fin short, 'n'ith 10-18 rays. (Caiostomina;.) 
e. Air-bladder in two parts. 
/. Lateral line complete and continuous ; scales small, 55-115 in the 
latei’al line. 
q. Fontanelle none Pantosteus, 63. 
gg. Fontanelle present. 
h. Mouth inferior, small, with thick papillose lips. 
Catostomus, 64. 
hh. Mouth very large, terminal, oblique; lii)s thin and nearly smooth. 
i. Pharyngeal bones moderate, with teeth of medium size. 
Chasmistes, 65. 
a. 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 Erimyzox, 67. 
gg. Lateral line more or less developed.. Mixytrewa, 68. 
ee. Air-bladder in three parts ; fontanelle present ; scales large ; lateral 
line complete. 
j. Mouth normal, the lower lip entire or merely lobcd. 
k. Pharyngeal bones moderate, the teeth compressed, grad- 
ually larger downwards; mouth moderate or small, the 
lips usually plicate Moxostoma, 69. 
kk. 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. 
Placopharyxx, 70. 
jj. Mouth singular, the upper lip not protractile, greatly en- 
larged, the lower lip developed as two separate lobes, 
pharyngeal bones and teeth ordinary Quassilabia, 71. 
59. — iCTSOUtlS Eafinesque. 
Buffalo-fishes. 
(Eafinesque, Ichth. Oh. 1820, 55: tyi)e AmModon Jjuhahis Eaf.) 
Head very large and strong, wide and deep ; its lengtli 3J-3| 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 narrow. Fontanelle large, well 
open. Opercular api)aratus largely developed; the suboperculuui 
broad ; the operculum broad, strongly furrowed. Mouth verj’ large for a 
suclcer, 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. Alandible very strong, 
oblique, placed at an angle of 45° or more when the mouth is closed, its 
posterior end extending to beyond oj)posite the front of the eye, its 
length a little less than one-third that of the head. Li^ts 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. Xat. Mus. No. IG 8 , 
