26. ACIPEXSERID^ ACIPEXSER. 
85 
ally have been unduly multiplied, particularly by Auguste Dumeril, 
who has found upwards of forty of them in the museum at Paris. 
The actual number of American sturgeons does not exceed 7, aud is 
more likely still less. The changes with age are considerable ; the snout 
in particular becomes much shorter and less acute, and the roughness 
of the scales is greatly diminished ; the ventral shields sometimes disap- 
pear altogether. The number of plates, although one of the best spe- 
cific characters, is subject to considerable variations. 
{AcipenseridcB Giiuther, viii, 332-345.) 
* Spiracles present ; snout subconic ; rows of bony shields distinct throughout. 
Acipenser, 47. 
Spiracles obsolete j snout subspatulate ; rows of bony sliields confluent on the tail. 
SCAPHIRRHYXCHOPS, 48. 
47.— ACIPEjVSER* Linnaeus. 
Sturgeons. 
(Artedi, Linn. Syst. Xat. : type Acipenser siurio L.) 
Snout subconical, more or less depressed below the level of the fore- 
head. A small spiracle over the eye. Caudal peduncle moderately 
long, deeper than broad, the rows of bony bucklers distinct to the base 
of the caudal fin. -Tail not produced into a filament, its tip surrounded 
by the caudal rays. Gill-rakers small, narrowed or lanceolate. Pseii- 
dobranchiae present. Species numerous. (Latin acipenser^ a sturgeon ; 
from azj<r, point ; Trei/ra, five ?) 
74. A. StsiB’io L . — Common Sturgeon. 
Snout rather sharp, nearly as long as the rest of the head, becoming 
comparatively shorter and blunter with age. Barbels nearly midway 
between mouth and tip of snout, shortish, not reaching the mouth. 
Gill-rakers small, slender, xjointed, sparse, not longer than the pupil. 
*M. Duuidril (Hist. Xat. Poiss. ii, 89) divides this group into six subgenera, as fol- 
lows : 
a. Spines of dorsal shields situated near their middle. (Jlesocenfres.) 
b. Stellate plates none. 
c. Scutella (between large shields) disclosed without order Huso. 
cc. Scntella disposed in quincunx Acipenser. 
bb. Stellate plates numerous Antaceus. 
aa. Spiues of dorsal shield at the posterior extremity. {Opislhocentres.) 
d. Stellate plates none. 
e. Lip emarginate Sterletus. 
ee. Lip entire Lioniscus. 
dd. Stellate plates numerous Helops. 
The same species at different ages may frequently belong to two or more of these 
Bubgenera. 
