POLYODON PADDLE-FISHES 17 



membranes connected, 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 denti- 

 cles; a continous 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 obvious use, and 

 regarded by Kofoid as "an expanded sense organ" merely; 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 de- 

 pendence, although one of our largest species, on the semi-micro- 

 scopic 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 river channels 

 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 

 sparingl3^ coming only from the central and southern regions of 

 Illinois (Ohio R., at Cairo, and Illinois R., at Meredosia and Ha- 

 vana). 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 abundant throughout the year as far north as 

 Havana, w^here 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 record, 

 reported by Drs. Jordan and Evermann from Lake Manitou, Indiana, 

 ^Yeighed 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 tb. 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 w-hich are spoonbill, shovel -fish or 

 shovel-cat, duck-bill cat, and spade-fish. Perhaps the earliest 



