SCAPHIRHYNCHUS SHOVEL-NOSED STURGEONS 27 



SCAPHIRHYNCHUS PLATORHYNCHUS (Rafinesque) 

 (shovel-nosed sturgeon) 



Rafinesque, '20, Ichth. Oh., 80 (Acipenser). 



G., VIII, 345 (cataphractus) ; J. & G., 88 (Scaphirhynchops) ; M. V., 34; J. & E,, 

 I, 107; N., 51 (Scaphirhynchops); J,, 69 (Scaphirhynchops); F., 85 (Scaphirhyn- 

 chops); L., 8. 



Body comparatively elongate; depth 6.7 to 11.7 in length; distance 

 from gill-opening to front of dorsal fin 2.1 to 2.2 in length without caudal; 

 length 2 to 3 ft* Color pale olive, darker above, where the color is 

 often a yellowish brown; belly whitish. Hea'd 3.5 to 3.8 in length of 

 head and body; rostrum comparatively short and wide, its greatest 

 width 1.3 to 1.6 in its length; interorbital space 3.3 to 3.7 in head; 

 eye S.3 to 8.3 (usually less than 7) in interorbital space; mouth wide, 

 1.6 to 1.9 in greatest width of rostrum; labial papillae well developed; 

 barbels flattened, the anterior edge furnished with one, and the pos- 

 terior edge with two rows of branched fringe-like pectinations; inner 

 barbels 1.1 to 1.4 in length of outer; gill-membranes meeting at the 

 isthmus in a rather shallow and usually quite obtuse angle, the mem- 

 branes foreshortened, as a rule falling short of the notch in the pectoral 

 shields; gill-rakers 12+5, 2- to 5-pointed on the lower half of arch, the 

 upper surface of which is a narrow edge, scarcely separating the outer 

 and inner rows of rakers. Dorsal rays 28 or 29, length of base of fin 12 

 to 14.3 in length of head and body; anal rays 17 or 18, ventral 21 or 22, 

 pectoral 43 or 44 ; caudal filament very much elongated in younger speci- 

 mens. Dorsal scutes 17 or 18, lateral 42 to 47 (usually 42-44) , ventral 11 

 to 13 ; spines of dorsal and lateral scutes falling considerably short of their 

 posterior edge ; area on body between dorsal and lateral and between 

 lateral and ventral series of scutes entirely covered with small, irregu- 

 larly shaped scale- like plates; belly and breast completely armored, the 

 plates subrhombic in form, becoming much smaller forward. 



This fish is fairly common in the Mississippi, Ohio, and Missouri 

 rivers, and in the other larger streams of the Mississippi Valley, 

 being more abundant southward. Little is -known of its habits. It 

 spawns between April and June, probably ascending smaller streams 

 for that purpose. The stomachs of two specimens studied by us 

 were found to contain considerable quantities of a greenish 

 gnat larva (C'eratopogon), a small number of nymphs of May- 

 flies (Hexagenia), a single dragon-fly nymph (Libellula pulchella), 

 which occurs on bottom mud in comparatively shallow water, 

 and a few caddis-fly larvas {Phryganeidce) . 



* Of 41 males and 21 females recently examined by Dr. Kvermann (Rep. U. S. 

 Fish Comm., 1901, pp. 285-286) the average length and weight for females was 

 25.4 inches and 3.24 fb, the largest female being but 29.5 inches long and weighing 

 4.75 lb, while males averaged 21.7 inches and 1.89 rh, the longest being 27 inches. 

 These measurements are considerably under those usually assigned in the literature, 

 and it seems probable that the species rarely reaches a length greater than 3 feet. 



