626 EXPLANATION OF THE PLATES. 
calcareous nodules; 6, base of the same; ec, d, shell 
membrane ; 500 diam.; fig. 43a, a nodule seen from the 
outside, 500 diam. ; fig. 43b, piece of a nodule in profile, | 
500 diam. ; fig. 43c, organic matrix of nodule, the lime 
dissolved out; a, its surface ; 6, its base; 500 diam.; fig. 
44, rows of nodules of a partially formed shell, 20 diam. ; 
fig. 44a, heaps of young nodules, 500 diam.; fig. 45, inner 
surface of shell membrane, 500 diam. Chelydra serpen- 
tina. 
Fig. 46. Openings in the egg-shell of Ozotheca odorata, 20 
diam. 
PLATE IXb. 
[ Figs. 9, 9a, and 10, from nature, by A. Sonrel; the other figures by 
H. J. Clark.] 
Fig. 1. Egg of Nanemys guttata, nat. size, from above; 
from the oviduct; for age, see Pl. 11, fig. 3. 
Fig. la. Egg of Nanemys guttata, nat. size, from above ; 
from the oviduct, June 3d, 1854; for age, see Pl. 10, fig. 
12, 18, 14, 15. 
Fig. 2. Profile, and fig. 2a, from above. Chrysemys picta, 
nat. size; from the oviduct, June 3d, 1852; for embryo, 
see Pl. 11, fig. 2. 
Fig. 3. Profile of an egg of Cinosternum pennsylvanicum, 
Alcoholic 
preparation. Fig. 3a, one of the layers of albumen; a, 
nat. size; from the oviduct, July 3d, 1856. 
the surfaces in profile ; 6, the interior; 25 diameters. 
Fig. 4. Profile, and fig. 4a, from above ; nat. size; from the 
oviduct, June 2d, 1854. Glyptemys insculpta. Alco- 
holie preparation ; for embryo, see Pl. 11, fig. 6. 
Fig. 4b. View from above of an egg without a shell, nat. 
size; from the oviduct. *Glyptemys insculpta. Alcoholic 
preparation. 
Fig. 5. Profile of the egg of Chelydra serpentina, nat. size ; 
from the oviduct, June 12, 1854. 
Fig. 6. Egg of Platypeltis ferox; from the oviduct, Aug. 
20, 1856; nat. size. Alcoholic preparation. Fig. 6a, 
portion of a layer of albumen; a, surfaces in profile; 6, 
the interior; 20 diam. Fig. 6b, albumen from the deeper 
layers; a, b, c, the oval granules, trending in three dif- 
ferent directions; 500 diam. Fig. 6c, inner layer of shell 
membrane; a, b, the oval, elongated granules, trending 
in two different directions; 500 diam. Fig. 6d, shell mem- 
brane, just outside of the inner layer (fig. 6c); a, gran- 
ules in strings; 0, finer granular strings; 500 diam. Fig, 
6e, a, b, c, three layers from the middle of the thickness 
of the shell membrane; 500 diam. Fig. 6f, from the mid- 
dle of the membrane; a, separate granules; }, fine 


fibres ; 500 diam. Fig. 6g, shell membrane next to the 
shell, 500 diam. 
Fig. 7. Profile and fig. 7a, from above ; nat. size; just laid, 
date lost. Thalassochelys Caouana. Alcoholic prepa- 
rations. 
Fig. 8. From above; nat. size; one week since laid; the 
same species as fig. 7. 
In all the figures of these eges, from fig. 1 to fig. 8, a desig- 
nates the albumen outside of the yolk sac, a’ the albumen 
inside of the yolk sac, s the shell, y the yolk, y' the sur- 
face of the yolk, e the embryonic disc, va the vascular 
area. 
Fig. 9. Portion of the oviduct containing an egg, nat. size ; 
ma, its mesenteric peritoneum; fig. 9a, slightly magnified 
portion of the oviduct to show the numerous bloodves- 
sels, and the pigment following their courses. Glypte- 
mys insculpta. 
Fig. 10. The left ovary and oviduct, from below, nat. size ; 
ov, ov', the oviduct ; ov*, its posterior end; p, the pavil- 
ion, or anterior opening; pr, ramifications of pigment 
cells; 01, the urinary bladder. Chrysemys picta. 
Fig. 11. Right ovary and oviduct, seen from below, nat. 
size; i, the intestine; ¢/, the corpora lutea, or cicatrices ; 
m, the mesenteric peritoneum of the oviduct; p, the 
pavilion ; e, e, e, é, four eges covered by the oviduct. 
Glyptemys insculpta; opened May 20, 1854. 
PLATE 1IXc. 
[Figs. 1, 2, 8, from nature, by H. J. Clark, the others by A. Sonrel.] 
Fig. 1. The same as PI. 8, fig. 12, on a larger seale. a, a', the 
two layers of the stroma; b, tunica granulosa; c, zona 
pellucida; d, embryonal membrane ; d', profile of d; vs, 
yolk sac; e, outer layer of fine yolk granules; f, inner 
layer of coarse yolk granules; g, Purkinjean vesicle. 
Fig. 2. Diagramic profile of an egg after the albumen has 
become partially absorbed. The same as PI. 11, fig. 4, 4a. 
a, the shell; }, shell membrane ; }/, albumen ; L’’, inner- 
most and densest layer of albumen; c, zona pellucida; 
d, embryonal membrane ; e, germinal layer; e’, embry- 
onie disc; 7, surface of the yolk; a/, albumen within the 
yolk sac. 
Fig. 3. Actual view of the interior of the embryo and its 
envelopes, seen from the front, to show the relations of 
the vascular system. The red color corresponds to the 
ventricle (p) and the arterial system of the body and 
yolk ; the blue to the auricles (7) and the venous system 
of the body and yolk; the yellow to the arterial system 



a 
