EXPLANATION OF THE PLATES. 
[Diam. stands for diameters, and the figures for the number of diameters any object is magnified; i. e., 500 diam, after fig. 1, Pl. 8, means 
that all the objects represented in that figure are magnified 500 times their natural diameter, etc.] 
PLATE I-VIla. 
[ All the figures of these Plates were drawn from nature, by A. Sonrel.] 
These Plates require no special explanation. Pl. 1 to 6 
represent young Turtles in their natural size at the time 
of hatching, or soon afterwards. Most of them are repre- 
sented from three sides, in profile, from above and from 
below; and frequently a front view of the head, and occa- 
sionally of the whole animal, is added. The attitudes are 
all natural, and in most cases copied from the living ani- 
mal. PI. 6, fig. 10-12 represent an embryo of Ozotheca 
odorata from the middle period of incubation ; fig. 17, a 
transverse section of the body of a young Thalassochelys 
Caouana ; e, is the spinal marrow; /d, the neural arch; 7, 
the lungs; ¢, the windpipe ; mp, the pectoral muscle; 7, 
the liver; h/, the aorta; n*, the esophagus; nés, the shoul- 
der muscles; re, the body of the vertebra; fig. 18-32, a 
series of embryos of Thalassochelys Caouana; fig. 30-32, 
a week old; fig. 28, and 29, two weeks old; fig. 26, and 
27, three weeks old; fig. 24, and 25, four weeks old; fig. 
22, and 23, five weeks old; fig. 20, and 21, six weeks 
old; fig. 18, and 19, seven weeks old. Pl. 7, and 7a, 
represent the mature eggs of many species, with frag- 
ments of the shell magnified. 
PLATE VIII. 
[ All the figures of this Plate were drawn from nature, by H. J. Clark.] 
Fig. 1, a, b,c, c', d,e, f, g, h, i, j,k, l,m, n, 0, p. Ovarian 
eggs of Chrysemys picta. All except c, 500 diam., and 
c, 1100 diameters. 

Fig. 1, 1}, o. 
ing each an egg, 500 diam. 
Fig. 2, 3, 3a, 4, 6, 6a, 7, 8, 8a, 9a, 10. 
picta ; fig. 8, 25 diam.; the others, 500 diam. 
Fig. 5. 
diam. 
Fig. 9. Same as fig. 5. 
500 diam. 
Fig. 11. Ovarian egg of Ch. picta, 25 diam.; fig. 11b, the 
same as fig. 11, natural size; fig. 114, the same, 500 
Two Graafian follicles of Ch. picta, contain- 
Ovarian eggs of Ch. 
Graafian follicle inclosing an egg of Ch. picta; 500 
Ch. picta, and Nanemys guttata; 
diam. ; a, its yolk granules, 1100 diam. 
Fig. 12. Graafian follicle inclosing an egg of Ch. picta, 300 
diam.; a, stroma; }, tunica granulosa; c, zona pellu- 
cida; d, embryonal membrane ; e, f, the yolk. 
Fig. 13, and 13a. Ovarian eggs of Ch. picta, and Nanemys 
guttata; fig. 13, 25 diam.; fig. 13a, 500 diam. 
Fig. 14. Graafian follicle and egg, 25 diam.; fig. 14a, Pur- 
3D) ~ 
kinjean vesicle of the same, 500 diam. 
Fig. 15. Ovarian egg of Ch. picta, 500 diam. Fig. 15a, 
a,b, c, d, e, f, f*, mesoblasts of the Purkinjean vesicle ; 
a to f, 1100 diam.; /', the same as f on an exaggerated 
scale. 
Fig. 16. 
diam. ; fig. 16b, albuminous globule of fig. 16a, 500 diam. 
Ovarian egg, 25 diam.; fig. 16a, the same, 40 
Ch. picta. 
Fig. 17, 17a. Ovarian eggs, 25 diam.; fig. 17b, yolk gran- 
ules of fig. 17, 500 diam.; fig. 17c, same as fig. 17, nat- 
ural size. Ch. picta, and Nanemys guttata. 
Fig. 18. Ovarian egg, nat. size; fig. 18a, the same, 25 diam. ; 
cD) 
fig. 18b, yolk of the same, 500 diam. Ch. picta. 
Fig. 19. Ovarian ego, 25 diam.; fig. 19a, the yolk, 500 
diam. ; fig. 19b, the egg, natural size. Ch. picta. 
oD? 
