FISHES STURIONIDAE POLYODON. 



357 



List of specimens. 



SCAPHIRHYNCHUS, Heck. 



GEN. CHAR. Body sub-fusiform, provided with five longitudinal series of pentagonal bony shields, extending from the head 

 to the fins, posterior to which it is depressed and completely covered by these shields. Upper surface of head cuirassed ; snout 

 prolonged. Mouth situated under the snout, toothless, and in advance of which are four, hanging down, barbels. Gill 

 covers well developed ; neither pseudo-branchiae nor spiracula. Gill openings separated under the throat by a rather narrow 

 isthmus. The vertebral column tapers off into a filament, very much elongated in the young. The general structure, aspect, 

 and relative position of the fins, as in Jlcipenser, except the caudal, which has no upper lobe. 



SYN. Scaphirhynchus, HECK, in Ann. Wien. Mus. Naturg. I, 1835 ; &, in Zool. Abhandl. Ann. Wien. Mus. Naturg. 

 I, 1841, 71 MULL, in Wiegm. Archiv fur Naturg. 1845, I, 106, & 119. 



This genus having been made the object of a very able monograph by Heckel, we must refer 

 our readers to it for further informations on this subject. 



SCAPHIRHYNCHUS PLATIRHYNCHUS, Bd. 



Shovel- Nose Sturgeon. 



SPEC- CHAR. Head terminated by a depressed, oval, spade-shaped snout. Lips provided with eight warty-fringed tufts. 

 Barbels nearer the mouth than the extremity of the snout, and fringed also. Anal fin nearer the vent than the caudal fin. 

 Brownisli above ; whitish beneath. 



SY N . Acipenser platorynchus, RAFIN. Ichthyol. Ohiens. 1820, 80. KIRTL. Rep. Zool. Ohio, 1838, 196 ; &, in Bost. Journ. 



Nat. Hist. V, 1845, 25. PI. viii, fig. 1. STOKER, Synops. 1846, 249. 

 Scaphirhynchus rafinesquii, HECK, in Ann. Wien. Mus. Naturg. I, 1835 ; &., in Zool. Abhandl. Ann Wien. Mus. 



Naturg. I, 1841, 72. PI. viii. 



Scaphirhynchus platirhynchus, BD. Iconogr. Encycl. II, 1850,238. 

 Shovel-fish sturgeon, spade-fish, shovel-head, flat-head, shovel-nose sturgeon, la Pelle, or Poisson pelle, VERNACULAR . 



This species is accurately figured and minutely described in Heckel s monograph alluded to 

 above. Space forbids us entering here into any kind of detail, and limit ourselves recording 

 two immature specimens procured along one of the various railroad surveys. 



List of specimens. 



POLYODON, Lacep. 



GEN. CHAR. Snout dilated into a thin, leaf-like blade; very much prolonged beyond the lower jaw. Mouth very large, 

 provided with numerous small teeth upon the palatine bones, uniting with the maxillaries to form the upper jaw. Branchial aper 

 tures very widely open, continuous under the throat; spiracula extant; opercle prolonged into a membranous, very long point. 

 Body and fins in general shape and aspect as in Jlcipenser ; but the skin is naked or else perfectly smooth. 



