DEVELOPMENT OE THE SKULL IN STURGEONS. 
183 
Plate. 
Pig- 
Stage. 
Number 
of times 
magnified. 
15 
13 
4 
Dissection of head of same; upper view .... 
2f 
55 
14 
4 
First of a series of sections of same. 
8 
j; 
15 
4 
Second section of same. 
8 
55 
16 
4 
Third section of same. 
8 
16 
1 
4 
Dissection of head of a younger specimen of same, 
7J inches long; side view. 
2f 
S3 
2 
4 
A vertical section of the head of another specimen, 
8 inches long. 
2| 
>3 
3 
4 
Dissected skull of young Acipenser sturio, 8 inches 
long; lower view. 
2| 
33 
4 
4 
The same; and same view, with visceral arches 
attached. 
2f 
33 
5 
4 
Visceral arches of same; upper view. 
2f 
55 
6 
4 
Fore part of same object; lower view 7 . 
H 
33 
7 
4 
Part of same as last; inner view. 
8 
33 
8 
4 
Fourth section of same (see Plate 15, figs. 14-16) . 
4 
55 
9 
4 
Fifth section of same .. 
4 
33 
10 
4 
Sixth section of same. 
4 
55 
11 
4 
Seventh section of same.. 
4 
33 
12 
4 
Eighth section of same. 
4 
17 
1 
4 
(Continuation of sections of head of Acipenser 
sturio , 8 inches long.) Ninth section of same . 
4 
55 
2 
4 
Tenth section of same.. 
4 
33 
3 
4 
Eleventh section of same .. 
4 
33 
4 
4 
Twelfth section of same. 
4 
33 
5 
4 
Thirteenth section of same .. 
4 
33 
6 
4 
Fourteenth section of same. 
4 
33 
7 
4 
Fifteenth section of same. 
4 
33 
8 
4 
Sixteenth section of same ........ 
4 
33 
9 
4 
Seventeenth section of same. 
4 
55 
10 
4 
Eighteenth section of same. 
4 
33 
11 
4 
Nineteenth section of same ........ 
4 
