160 REPORT OF STATE GEOLOGIST. 



Family ACIPENSERIDiE. 



Body elongate, fusiform. Skin with five rows of bony plates, between 

 which are numerous small bony deposits. Mouth rather small, pro- 

 jectile, toothless. Gill-rakers present, not slender. Dorsal and anal 

 fins far back. Vertical fins with fulcra. 



This family contains two genera, both of which are represented in 

 Indiana. 



* Snout depressed, shovel-shaped. Scaphirhynchus, p. 160. 



** Snout nearly conic. Acipenser, p. 161. 



Genus SCAPHIRHYNCHUS Heckel. 



Head broad and flat. Snout long, flat and pointed. A row of barbels 

 across the lower side of the snout. No spiracles. Gill-membranes con- 

 nected with the isthmus. Gill-rakers two rows on each arch, short, 

 broad, and flat. Caudal peduncle long, depressed and entirely covered 

 with bony plates. Tail ending in a long filament. 



Besides the single American species there are a few species found 

 in Asia. 



Scaphirhynchus platorhynchus (Raf.). 

 Shovel-nosed Sturgeon; White Sturgeon. 



Seaphirrhyneho'ps platyrrhynchus, Jordan and Gilbert, 1882, 8, 88 ; 

 Jordan, 1882, 2, 768 ; 12, 1884, 663, pi. 244; Scaphirhynchus platyrhyn- 

 chus, Jordan, 1888, 7, 34. 



The body rather slender, the head rather broad, becoming suddenly 

 broader just behind the eyes, then passing into the flat, pointed snout. 

 From the head the body tapers gradually to the tail, the upper lobe of 

 which ends in a long, slender filament. This filament covered with min- 

 ute bony plates. Caudal, dorsal, and anal fins rather small. Body pro- 

 tected by five rows of bony bucklers ; these separated in front of the 

 dorsal fin by spaces roughened by small bony deposits. Each plate with 

 a median ridge, which terminates behind in a sharp point. Behind the 

 dorsal the rows become confluent, thus entirely covering the caudal 

 peduncle. From the head to the dorsal fin there are about eighteen 

 plates in the dorsal row, and about thirty in the lateral row. Between 

 the pectorals and ventrals there are about tweh'« plates in the lowest 

 row. Head with a few short, backwardly directed spines. Its length 

 contained in distance from tip of snout to base of caudal about four 

 times. Snout one-half the length of the head. Barbels four. Lips 

 thin and soft ; the inside of the upper with numerous papillae. Color, 

 olive above ; pale below. Reaches a length of five, possibly of eight, feet. 



A very common fish in all the larger streams of the Mississippi Valley. 



