36 
Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. 
Ear 
Integument, Lateral Line 
Mouth 
Archenteron 
N 
ST 
| Vertical diameter of otocyst about. three-fifths of 
length. Middle third of floor expanded, forming a 
|broad shallow pouch (sacculus?). A shallow vertical 
| groove on mesial surface of otocyst, midway between 
anterior and posterior ends. 
28 |Sacculus a distinct thick-walled pouch from lateral 
side of posterior end of otocyst: Posterior end of, 
lateral canal-pocket lies immediately above sacculus; 
| marked off from utriculus above by a distinct groove; 
projects a little ventrally and posteriorly. Posterior 
canal-pocket a distinct pouch arising from the mesial 
surface of the otocyst, posterior to ductus endo- 
Iymphaticus; and projecting backward 120 u beyond 
posterior edge of lateral pocket. Ductus endo- 
Iymphaticus arises from dorsal third of mesial sur- 
face of otocyst, midway between anterior and pos- 
terior ends. Extends dorsally to roof of hind-brain, 
then turning at right angles extends posteriorly 
200 u. before fusing with epithelium of skin. 
29 |Sacculus flask-shaped in cross section, projecting 
posteriorly as a blind sac. Anteriorly, connected 
with utriculus. Lined with very high ciliated (?) epi- 
thelium. Antero-lateral and posterior canal-pockets 
enlarged distally. 
Anterior four-fifths of sacculus connected with 
utriculus by a stalk which is a little constricted 
|transversely. Ventral half of lateral canal-pocket 
|separated from utriculus. Posterior end projects 
|backward as a blind pouch. Posterior half of poSs- 
| terior canal-pocket separated from utriculus — cur- 
| ved a little laterally. Anterior canal-pocket not as 
| distinct as posterior and lateral. Horizontal limb of 
ductus endolymphaticus 250 u in length (by sections). 
30 
31 |Anterior canal separated from pocket dorsally, lies 
Integument composed of an inner layer of cuboidal or 
Epithelium of lower half of lateral surfaces, and ven- 
cuboidal, and an outer layer of exceedingly squamous 
cells. In head region, ventral to optic vesicles, two 
layers of cuboidal cells, — along ventral median outer 
layer high columnar. Dorsal to supra orbital placode, 
a single layer of squamous cells. Lateral line placode 
extends posteriorly to pectoral fin. 
Epithelium composed of an inner layer of cuboidal or 
columnar cells, and an outer layer of squamous cells. 
A_definite basement membrane present. Outer layer 
of cells markedly thickened (columnar) on ventral sur- 
face of head, mesial and anterior to olfactory pits, 
forming a rostral plate, thelateral and posterior bound- 
aries of which are distinguishable in external view. 
Supraorbital placode and lower part of postorbital 
placode visible in external view. Lateral placode ex- 
tends posteriorly to level of cloaca. (See note under 
remarks.) j 
Epithelium much as in preceding stage (No. 28). Mes- 
enchyma a little condensed below it. Outer cells of 
rostral plate about twice as high as those of inner 
layer. Viewed externally, supraorbital canal arises 
over middle of eye and is continuous ventrally with 
ethmoid canal. Ethmoid canal turns sharply mesially 
and joins angular canal below nasal pits. Praeoral 
canals continuous with angular and ethmoid; do not 
meet at median line. Angular canals turned mesiall 
at posterior ends, extending inward a little beyond 
angle of mouth. — Postorbital canal does not extend 
dorsally beyond lower edge of eye. Lateral placode 
extends to middle of caudal fin. 
Epithelium much as in preceding stage (No. 29) — outer 
layer of cells more squamous. Cells of outer layer 
of rostral plate apparently degenerating. In sections, 
ampullae appear in rostral plate as clusters of cells 
arranged like those of taste-buds. Outlines of rostral 
plate, as viewed externally, indistinct. Viewed ex- 
ternally, supraorbital canal extends posteriorly to above 
last gill slit. Postorbital canal joins supraorbital posterior 
to eye. 
tral surface of trunk, composed of an inner layer of 
y|bases of mandibular processes. 
Mouth opening as in preceding 
stage. Frontal process broader, 
projecting a little more from the 
head than in preceding stage (No.26). 
Mouth opening broadly oval in out- 
line, broader than long. Maxillary 
and mandibular processes meet ät 
an angle of nearly 100°. Anterior 
ends of maxillary processes much 
enlarged — separated by a shallow 
cleft approximately one-fifth as 
broad as mouth opening. Rounded 
frontal process projects into lower 
half of cleft. A shallow median 
groove separates bases of mandi- 
bular processes. 
Mouth opening lenticular in out- 
line, nearly three times as broad 
as long. Anterior ends of maxil- 
lary processes not prominent — 
separated at median line only by a 
faint groove. Frontal process over- 
hangs maxillary processes at median 
line. No line of separation between 
Mouth opening three times as broad 
as long. Maxillary processes separ- 
ated by a shallow median groove. 
Labial pockets appear as slight 
depressions Iying lateral to angles 
of mouth. 
t Lateral angles of mouth bounded — 
kam dorsal to utriculus. Middle portion of hori- |columnar cells, and one or two outer layers of squa- | by narrow elevated jaw-ridges. Up- 
zontal canal completely cut off from pocket. Con- | mous or, occasionally, cuboidal cells. "Mesenchyma | per jaw-ridge projects a little over 
|nections of anterior and posterior portions much | condensed below epithelium. In places, mesenchymal I Well defined labial pockets j 
| constricted. Posterior canal cut off from pocket for a | cells epithelioid in arrangement. Occipital canal lateral to jaw-ridges. 
considerable distance. Distinct expansion of antero- established. Anterior limbs of median canal system, 
|lateral ampulla. Canal between sacculus and utri- established, 
culus longer but not narrower than before. Sacculus 
|smaller in comparison with utriculus than in pre- 
ceding stage (No. 30). 
in front of nasal pits; no median part yet established. 
Ampullae appear externally as minute whitish thickenings 
of epidermis. Mandibular, postorbital, anterior and pos- 
terior infraorbital and 
— extend ventrally to a point somewhat 
orbital groups established. In 
If 
en 
Mn einer HH mn An 98 AD Fr 
Aal ER U RER, Ze 
section, ampullae appear as shallow depressions, which 
extend through 3—4 sections of 20 u and are lined with 
closely packed elongated cells ofinnerlayer ofepithelium. 
a 
Da} . . 1 
32 |Semicircular canals as in preceding embryo, except Epithelium as in preceding stage (No. 31). Epicranial | Jaw-ridges narrower and more pro- — j 
|for expansion of ampulla. A slight transverse con- | and hyoid groups of ampullae visible in external view. jecting than in preceding stage { 
|struction of sacculus, dividing it into sacculus proper (No. 31). Deep labial pockets, which 1 
jand lagena. Ductus endolymphaticus a little ex- are invaginated anteriorly. 1 
panded just ventral to horizontal limb. Horizontal 
limb extends 0.5 mm. posteriorly, opens to surface 
of body. IN 
