628 
between the germino-amniotie (a) and subsidiary (o') 
layers in the area pellucida; d, periphery of the area 
pellucida; e, edge of the primitive furrow, or of the 
spinal channel; ¢', cephalic region of the spinal nervous 
system ; ¢*, spinal marrow closed over; e', caudal portion 
of the same ; ¢’, lower floor of the spinal canal; f, verte- 
bre; 1, vertebral layer; /?, lower edge of the verte- 
bre ; f', upper edge; f°, outer or lateral limit of 
the vertebra ; g, chorda dorsalis; 7’, incipient vena ter- 
minalis; j°, dorsal artery; 1, intestino-subsidiary layer ; 
n®, stomach; n', esophagus; n°, mesenterium of the in- 
testine ; o', subsidiary layer ; p, musculo-cutaneous layer ; 
p’, musculo-costal layer; q, Wolffian bodies; q', their 
ducts; 7, liver; w, the feet. 
Fig. 1 corresponds to Pl. 10, fig. 12, 18, 14, 15. 
section. 
An ideal 
Fig. 2 corresponds to Pl. 11, fig. 1, 6, 6a; 25 diam. An act- 
ual longitudinal section. 
Fig. 3 corresponds to Pl. 11, fig. 8. Ideal longitudinal sec- 
tion. Fig. 3a, ideal transverse section of fig. 3. 
Fig. 4 corresponds to Pl. 11, fig. 5, 5a. Ideal longitudinal 
section. Fig. 4a, ideal transverse section of fig. 4, 
through the point e’. Fig. 4b, another transverse section 
through the point >, so as to include the upper and 
lower bend of the body. 
Fig. 5 corresponds to Pl. 12, fig. 1, la. An ideal trans- 
verse section at about midway between head and tail. 
(In this figure, the dots from the letter e, on the right, 
should extend to the next inner line, which runs close to 
f) 
Fig. 6. An actual transverse section close behind a’, fig. 2, 
Pl. 12; 40 diam. 
Fig. 7 corresponds to Pl. 18, fig. 7. Actual transverse sec- 
tion, near the posterior end of the body. 
Fig. 8 corresponds to Pl. 14, fig. 2, 2a. 
section of the embryo of Thalassochelys Caouana, just 
Actual transverse 
behind the fore legs, about 5 diam. 
Fig. 8a. 
g The same as fig. 8. Actual transverse section 
through the middle region of the body. 
Fig. 9. The same as fig. 8, 8a. Actual transverse section 
just behind the opening of the esophagus. Nanemys 
guttata, 12 diam. 
Fig. 9a. The same as fig. 8 and 9. Actual section across 
the root of the tail, 12 diam. 
Fig. 10 to 10d. Spermatie particles from the testicle of an 
adult turtle. Chrysemys picta; fig. 10, 10a, 500 diam. ; 
fig. 10b shows the swelling (a') at the base of the so- 
called head (a); 6, the tail; fig. 10c, another view of 
The 
origin of this swelling has not been traced in turtles; but, 
10b, showing that the swelling (a') is on one side. 

EXPLANATION OF THE PLATES. 
from its similarity to what has been seen in several other 
animals, we have no hesitation in pronouncing it to be 
the remains of the cell in which the particle was devel- 
oped ; fig. 10d, a perfectly mature particle, the most nu- 
merous and lively of all, free from the remains of the 
parent cell; figs. 10b, 10c, 10d, 1100 diam.; April 8, 
1856. 
Fig. 11. 
lower jaw; a, channel of the nerve; #, lateral cavities 
Longitudinal section of the right branches of the 
connecting with a; d, teeth of the suture; fig. 11a, 
transverse section of fig. 11; the letters a, b, the same ; 
c, cartilaginous strip in the sulcus inframaxillaris; *=-*, 
line through which the longitudinal section was made. 
About 12 diam. Chelydra serpentina, just ready to be 
hatched. 
Fig. 12. 
diam.; a, a’, cartilaginous part of the rib ; 4, its wings ; 
Transverse section of a rib and of the shield, 40 
c, the corium; c/, corium below the rib; d, fibrous lin- 
ing of the shield; e, epidermis. 
just hatched. 
Chelydra serpentina, 
PLATE X. 
[Fig. 2, 8, 4, 12, 13, 14, from nature, by H. J. Clark; the others by A. 
Sonrel. Excepting fig. 12, 18, 14, all were taken from the oviduct 
of Glyptemys insculpta.] 
In all the figures, a marks the region immediately around 
the embryonic area; a’, the “cones;” }, the space where 
segmentation is going on; c, the yolk; d, the albumen ; 
e, the segment masses beyond the embryonic dise. 
Fig. 1. 
seen from above; fig. 1a, the same, nat. size. 
The whole ege 
go, the shell being removed, 3 diam., 
This was 
the anterior or first egg in the left oviduct. 
Fig. 2. Deeper view of fig. 1. 
Fig. Anterior or first egg in the right oviduct. 
Fig. Second egg in the right oviduct. 
Fig. 
ey 
da da 03 
3 
4 
5. Third egg in the right oviduct. 
6. Third egg in the left oviduct. 
7. Second egg in the left oviduct. 
8. Fourth egg in the left oviduct. 
All the eges represented in fig. 1 to 8 were taken from the 
same turtle, May 27, 1854. 
Fig. 9. Fourth egg in the right oviduct. 
Fig. 10. Second egg in the left oviduct. 
Fig. 11. First egg in the right oviduct, 25 diam. 
Fie. 11a. The whole ege The 
2 go, without the shell, nat. size. 
same as fig. 11. 
Fig. 11b. The same as fig. 11. 
All the eggs represented in fig. 9 to 11b were taken from 
one turtle, May 28, 1854. 
The whole egg, 3 diam. 

