THE STURGEONS AND STURGEON INDUSTRIES. 
239 
alone is diagnostic; none of the young of the common species are dark-colored, while 
the characteristic dirty olive green or brownish, with a shade of green in it, is always 
markedly characteristic of the common species at all stages of its growth. Le Sueur’s 
incidental remark as to the length of the common species in his day shows, if his 
report signifies an average, that it has since then diminished in size. 
A. hrevirostris is never taken in the large gill-nets used in capturing the common 
form, for the reason probably that it never reaches a large enough size. This con- 
clusion is confirmed by the fact that sexual maturity is reached much earlier than in 
the common form as is proved by the condition of the reproductive organs of the suite 
of examples in my possession. Out of the series of five specimens the sex may 
easily be made out by inspection of the young roes and milts of four of them. The 
smallest specimen even, although only a little over 18 inches in length, has the internal 
reproductive organs far more developed than specimens of the common species of the 
same size. In fact, I have not been able to make out the sex with certainty by simple 
inspection with the naked eye, in specimens of the common species, as large as my 
largest examples of A. hrevirostris, measuring 23 inches in length. These data, taken 
in connection with the presence of the long lanceolate median fontanelle or fenestra 
on the top of the head of the sharp-nosed young of the common species, show that the 
latter matures much later and only after becoming much larger than the J-. hrevirostris. 
The latter probably corresponds to the sterlet of Europe as respects size and pre 
cocious maturity, but differs entirely from it in its dermal armature, which is essen- 
tially mesocentrous, while in the sterlet the dermal armature is opisthoceutrous. 
3. THE DERMAL ARMATURE OF THE BODY. 
The armature of the body and tail is subject to a good deal of variation in both 
of the species of sturgeons found in the Delaware. This is well shown by the follow- 
ing table, giving the number of dermal scutes found in the dorsal, lateral, and ven- 
tral rows in the young and adults of Acipenser sturio, and in the young and probably 
two-thirds mature stage of A. hrevirostris Le S. 
(The vulgar fractious iu thi.s table are used to indicate the number of scutes in the lateral and ventral 
rows of opposite sides of the body.) 
Specimens. 
Dorsal scutes. 
Lateral scutes. 
Ventral scutes. 
Preanal plates. 
Keniarks. 
10 
29 
10 
No. 2. A. sturio 
11 
26 
11 
do 
1)0. 
12 
30 
11 
Do 
13 
30 
11 
..do 
Do. 
11 
28 
10 
Do. 
11 
29 
10 
Do. 
10 
28 
10 
Do. 
11 
29 
Do. 
No. 9. A. sturio ... 
11 
29 
9 
do 
Adult. 
Average 
111 
28| 
log 
