N Ze 
ne Eu 
Set 
en 
20 
Normentafeln zur Entwicklungsgeschichte der Wirbelthiere. 
Desig- 
nation 
Measure 
Age Body Form 
ı No. 574 
| No. 165 | 
| No. 169 
| "No. 172 
No. 149 
Trans. 
No. 151 
Front. 
No. 150 
Sag. 
Trans. 
No. 576 
Front. | 
No. 575 
Sag. | 
No. 164 
Trans. 
No. 166 
Front. 
Sag. 
No. 167 | 
Trans. 
No. 168 
Sag. 
Front. 
No. 170 
Trans. 
No. 171 
Sag. 
Front. 
7.0 mm 
7.0 mm 
6.0 mm 
15.0 mm 
15.0 mm 
14.5 mm | 
12"), 
days 
| 
Primitive 
Streak 
Primitive Segments 
Head bend and neck bend nearly right-angled. Caudal end of body 
bent upward and to right. Trunk between point of neck bend and 
region of hind limbs bends within a wide obtuse angle. 
Head bend and neck bend nearly right-angled. Caudal end of body 
| bent upward and a little to the right. Trunk between point of neck 
bend and region of hind limbs bends within a wide obtuse angle. 
Brow overhangs pericardial wall. 
Head bend and neck bend nearly right-angled. Caudal end of body 
bent upward nearly in median line. Back nearly straight from a 
point about half way between fore and hind limbs to the place of 
neck bend. Head overhangs heart chamber. Tail nearly touches 
brow. 
Head bend nearly right angled. Neck bend obtuse-angled. Caudal 
end of body bent up between hind limbs. Back nearly straight from 
region of neck bend to level of hind limbs. Head overhangs heart 
chamber. Abdomen as prominent as thorax. Hind limbs nearly in 
direct line with fore limbs. 
Neck bend a wide obtuse angle. Head somewhat elevated. A 
striking prominence in region of mid-brain. Back straight from 
region of neck bend to level of hind limbs. Tail projects ventrad 
in median line. Abdomen more prominent than thorax. 
Very similar to condition at I6 days. A striking prominence in 
region of mid-brain. 
Angle at vertex (head bend) is obtuse. Neck bend a wide obtuse 
angle. Head considerably elevated but projects ventrad of body. 
Back quite straight from region of neck to region of hind limbs. 
Short tail lies between hind limbs. 
Essentially the same condition as at 17 days. Head a little more 
elevated. 
Body form in essentially similar condition to that at ı8 days; the 
head a little more elevated. 
In heart region, cutis plate and muscle plate of 
myotome are not very distinct, especially the 
former. Both are considerably modified. Mes- 
enchyma largely replaces the cutis plate. 
In region of heart, cutis and muscle plates can 
not be clearly made out. There are primitive 
segments in caudal end of body. 
In region of heart, there is no distinct myotome. 
There are myotomes in the caudal end of the 
body. 
ee are still recognizable in caudal end 
of body. 
Still a trace of myotomes in caudal end of body. 
eroKore re Mehr, 
a a er u er u Pe Da ie ren ee a a ee A I 
