POLYODON — PADDLE-FISHES 17 



free from isthmus; gill-rakers long and slender and exceedingly numerous, 

 in a double series on each arch. Dorsal fin posterior, nearly over anal, its 

 insertion behind base of ventrals, on a raised fleshy base; dorsal rays 50 to 

 65; caudal heterocercal, but scarcely unequally furcate, the upper lobe with 

 13 to 20 well-developed fulcra; anal rays about 60. Body scaleless; tip of 

 caudal peduncle and sides of upper caudal lobe with small elongate rhombic 

 plates; margins of gill-openings, under flap, with numerous corneous shagreen- 

 like denticles; a continuous lateral line of ramifying tubes from eye along 

 upper part of head to base of caudal fin; upper and under side of paddle, 

 top and sides of head, and opercular flap much sprinkled with sensory pits, 

 distributed in small circular patches. 



This is, on the whole, the most remarkable of our fresh- 

 water fishes. Its large, paddle-shaped snout, of no very obvi- 

 ous use, and regarded bj^ Kofoid as "an expanded sense organ" 

 merel}^; its enormous mouth with weak and slender-boned jaws, 

 very finely toothed in the young, but smooth and toothless in 

 the adult; the elaborate straining apparatus borne on its gill- 

 arches; and its dependence, although one of our largest species, 

 on the semi-microscopic animals and plants of the plankton as 

 the most important element of its food, give it a unique place in 

 the classification and the economy of the fish population of our 

 larger rivers. 



It is found in the bayous, lowland streams, and rivers chan- 

 nels of the Mississippi Valley, northward to Minnesota and 

 Wisconsin, and southward as far as Louisiana and Texas. It is 

 not found in the basin of the Great Lakes, and is rare in any 

 except the larger water bodies of its range. It is represented 

 in our collections rather sparingly, coming onty from the central 

 and southern regions of Illinois (Ohio R., at Cairo, and Illinois 

 R., at Meredosia and Havana). It is abundant in the bayous 

 of the Mississippi about Alton. It is rather rare now in the 

 Illinois River above Meredosia, though it was formerly abun- 

 dant throughout the year as far north as Havana, where it is 

 now taken only in spring. Its entrance to the upper Illinois 

 is generally thought to be obstructed by the dams. 



The paddle-fish grows to a great size. The largest on rec- 

 ord, reported by Drs. Jordan and Evermann from Lake Man- 

 itou, Indiana, weighed 163 lb. Mr. Wm. C. Harris records an 

 example, from Lake Tippecanoe, Indiana, which was 6 ft, 2 in. 

 in length, and 4 ft. in greatest circumference, and weighed 150 

 ft). It is not ordinarily taken heavier than 30 to 50 lb. 



Various names in addition to those here used have been 

 applied to this fish, the commonest of which are spoonbill, 



