Normal plates of the development of the rabbit (Lepus cuniculus L.). 
Fig. 33 (X 5). 
The description is taken from a specimen closely similar to that figured and of the 
same age. Embryo of 161/, days after coitus. Longest diameter, 17.6 mm.; brow-snout, 5.0 mm.; 
vertex-brow, 7.0 mm. ZENKER fixation. This 161/,-day embryo does not differ much from that 
of 16 days except in some increase in size. The bends of the head, neck and caudal region are in essentially 
the same condition. Compare the description of the 16-day embryo. The more noticeable changes are 
the following: the snout projects a little more; the digits in manus and pes are somewhat more clearly 
separated; the pinna is a little larger and more pointed. There is still a striking prominence in the 
region of the mid-brain. Compare, for internal development, Table No. 21. 
Fig. 34 (X 5). 
The description is taken from a specimen closely similar to that figured and of the same 
age. Embryo of 17 days after coitus. Longest diameter, 21.0 mm.; brow-snout, 7.0 mm.; vertex- 
brow, 8.0 mm. ZENKER fixation. The angle at the brow is nearly right. The angle at the vertex 
is obtuse. The neck bend forms a wide obtuse angle. The head is considerably elevated but projects 
ventrad of the body. The caudal end of the body curves around gradually until the short tail lies between 
the hind limbs. The snout is quite prominent. The mouth and external nares face downward (caudad). 
There are hair anlagen on maxilla and mandible, four above the eye, one below it and a few between the 
mandible and the ear. These anlagen are numerous on the lateral and somewhat on the ventral aspect 
of the trunk between the fore and hind limbs. There is a small elevation in the region of the mid-brain. 
The digits in both manus and pes are distinctly separated; five in the manus, four in the pes. The palm 
faces caudad, the sole mesad, nearly meeting its fellow. Compare, for internal development, Table No. 22. 
The few more important changes in this 17-day embryo as compared with that of 16'/, days are 
the following: the neck bend is further reduced and in consequence the head is more elevated; there is 
not such a striking prominence in the region of the mid-brain; the snout and mandible are somewhat more 
prominent; hair anlagen appear on the trunk; the limbs are clearly larger; the digits separated. 
Fig. 35 (X 3). 
The description is taken from a specimen closely resembling that figured and of the 
same age. Embryo of 18 days after coitus. Longest diameter, 24.4 mm.; brow-snout, 8.0 mm.; 
vertex-brow, 7.2 mm. ZENKER fixation. 
This ı8-day embryo does not show many important differences from that of 17 days, the description 
of which may be referred to; the former when compared with the latter shows the following changes: the 
head is a little more elevated; the snout and mandible are somewhat more prominent; the eyelids are more 
developed; there is a general increase in size; hair anlagen are more numerous. Compare, for the internal 
development of this ı8-day embryo, Table No. 23. 
Fig. 36 (X 5). 7 
The description is taken from a specimen closely similar to that figured and of the same 
age. Embryo of 20 days after coitus. Longest diameter, 29.0 mm.: brow-snout, IO.o mm.; 
vertex-brow, 8.0 mm. 
The bend at the brow forms an obtuse rather than a right angle. The bend at the 
vertex forms an obtuse angle. The neck bend forms a wide obtuse angle. The head is 
2* 
