DEVELOPMENT OE THE SKULL IN STURGEONS. 
LSI 
Explanation of the Plates. 
Plate. 
Fig. 
Stage. 
Number 
of times 
magnified. 
12 
1 
1 
Larva (recently hatched) of Acipenser ruthenus, 
5J- millims. long. 
17 
55 
2 
1 
Larva of same, 6^ millims. long. 
15 
55 
3 
1 
Under view of head of same specimen .... 
15 
55 
4 
2 
Head of larva of same, 8-J millims. long.; side 
view. 
15 
55 
5 
2 
The same head; lower view. 
15 
55 
6 
2 
The same head; upper view. 
15 
55 
7 
2 
A larger larva of same, 9^ millims. long .... 
10 
55 
8 
2 
Head of same larva; upper view. 
10 
55 
9 
3 
A still larger larva of same, 134 millims. long . . 
15 
55 
10 
2 
First of a series of transversely vertical sections of 
a larva of Acipenser ruthenus, 9J millims. long. 
40 
55 
11 
2 
Second section of same. 
40 
55 
12 
2 
Third section of same. 
40 
13 
1 
2 
Fourth section of same. 
40 
55 
2 
2 
Fifth section of same. 
40 
55 
3 
2 
Sixth section of same. 
40 
55 
4 
2 
Seventh section of same. 
40 
55 
5 
2 
Eighth section of same. 
40 
55 
6 
2 
Side view of dissected head of another larva, 
9^ millims. long. 
26f 
5 5 
7 
2 
Under view of head of larva of Acipenser ruthenus, 
9^ millims. long. 
14 
55 
8 
3 
Head of a larger larva of same, 13J millims. long; 
under view. 
14 
55 
9 
3 
The same object; upper view. 
14 
55 
10 
3 
Horizontal section of head of a larva of the same, 
134 millims. long. 
40 
55 
11 
3 
Larva of Acipenser ruthenus, 13^ millims. long; 
side view of dissected head. 
20 
55 
12 
3 
Visceral arches of the same head ; upper view . 
20 
