25. POLYODONTID^ POLYODON. 
83 
lions teeth. Similar teeth on the palatines. ^To tongue. Spiracles 
jiresent. Operculum rudimentary, its skin iiroduced behind into a long, 
acute llap. ZSTo pseudobrauchim nor opercular gill. Gills 4^-. Gill- 
rakers loug, in a double series on each arch, the series divided by a broad 
membrane. Gill membranes considerably connected, free from the isth- 
mus. A single broad branchiostegal. Xo barbels. Aostrils double, at 
base of blade. Lateral line continuous, its lower margin with short 
branches. Dorsal fin well back, of soft rays only. Aual similar, rather 
farther back. Tail heterocercal, the lower caudal lobe well developed, 
so that the fin is nearly equally forked. Sides of the bent portion of the 
tail armed with small rhombic plates. Caudal fin with fulcra. Pec- 
torals moderate, placed low. Ventrals abdominal, many-rayed. Air- 
bladder cellular, not bifid. Pyloric coeca in the form of a short, broad, 
branching, leaf-like organ. Intestine with a spiral valve. 
Two genera known, Folyodon and Fsejiliurus, each of one species. Sin- 
gular fishes, inhabiting the fresh waters of the United States and China. 
They feed chiefly on mud and minute organisms eontained in it, stirring 
it up with the spatulate snout. 
{Pohjodontidw Giiuther, viii; 346-347.) 
* Gill-rakers very fine and nnmerous; caudal fulcra small and numerous. 
POLYODON, 46. 
46. — POLYODON Lac^pede. 
Faddle-fislies. 
(Spatularia Shavf : PlatirostraJ^e Sneiii.) * 
Lacdpede, Hist. Nat. Poiss. i, 402, 1708: type “Polyodon feuiUe” = P. folium Blocli.) 
Gill-rakers exceedingly numerous, very slender ; spatula broad. Cau- 
dal fulcra 13 to 20 in number, of moderate size. Eivers of the United 
States, many; 6ddjv^ tooth.) 
yS. P. spntimla. (Walk.) J. & G. — Paddle-fish ; Spoon-hill Cat ; Duck-hill Cat 
Color olivaceous, rather pale. Opercular flap very long, nearly reach- 
ing to ventrals. Spatula broad. Premaxillary extending far behind 
the small eye. Skin smooth, or nearly so, except the rhombic plates on 
the sides of the tail. Ventrals near the middle of the body; dorsal 
well behind them; anal mostly behind the dorsal, and somewhat 
larger; these fins somewhat falcate. Fin-rays slender. Spiracle with 
a minute barbel. Isthmus papillose in the young. Spatula 24 to 4 times 
in length. Whole head, with opercular flap, more than half length. 
Head, without spatula or flap, about 5. D. 50-G0 ; A. 50-05 ; V. 45. 
