344 NEW-YORK FAUNA. 
SUB-CLASS I. CARTILAGINOUS FISHES. 
Bones cartilaginous. Cranium divided by indistinct sutures. Gulls generally fixed ; the 
membrane without rays. Maaillary and intermawillary bones either wanting or rudi- 
mentary, the palatines or vomer alone supplying their place. 
Ozs. The fishes of this sub-class form a small group, neither superior nor inferior to the 
others, but form with them a parallel series. The skeleton contains no bony fibres, but cal- 
careous grains. The gelatinous substance, which in other fishes fills the intervals of the 
vertebra, and communicates from one to the other only by a small hole, forms in several genera 
a continuous cord which perforates them all. 
ORDER IL ELEUTHEROPOMI. 
Gills pectinated, free as in ordinary fishes, with one large external aperture on each side, 
furnished with a strong opercle ; without rays. Upper jaw formed by the palatine bone, 
firmly united to the maaillary ; intermaaillary rudimentary. 
FAMILY STURIONID:. 
Body elongated, with large osseous plates or tubercles arranged in longitudinal rows. Mouth 
placed beneath, very protractile, and without teeth. 
Oss. A small group, containing at present about fifteen species, but not thoroughly examined. 
GENUS ACIPENSER. Linneus. 
Snout prominent ; nostrils and eyes lateral. Four pendent barbels on the under side of the 
snout. Air-bladder large, and communicating by a large hole with the stomach. Dorsal 
and anal on the posterior part of the body. 
THE LAKE STURGEON. 
ACIPENSER RUBICUNDUS, 
PLATE LVIII. FIG. 191. 
Acipenser rubicundus. Lesvrur, Trans. Am. Phil. Soc. New series, Vol. 1, p. 388, pl. 12. 
A. id.. The Ruddy Sturgeon. RicHarpson, Faun. Bor. Am, Vol. 3, p. 284. 
A, id. Kirtianp, Report on the Zoology of Ohio, p. 196. 
Characteristics. Body of a ruddy hue. Head flat between the eyes. Lateral series lozenge- 
shaped, oblique, and thirty-nine in number. Length four feet. 
