i6 



Normentafeln zur Entwicklungsgeschichte der Wirbeltiere. 



Stage 



Length 



External 

 features 



Chondral 

 skeleton 



Bony 

 skeleton 



Nervous 

 System 



Integument 



Eye 



Otocyst 



Nose 



Hypo- 

 physis 



Mouth 



30 



Ten day 



larva. 



19 mm 



Growth of post- 

 anal region 

 coramencing. 

 External gills 

 becomingraised 

 up ona common 

 base. Mouth in- 

 dicated by 

 groove. 



31 



Thirteen 



day 



larva. 



(12-15 

 daj's.) 



20 mm 



Median fin fold 

 much increased 

 in size. Appear 

 ance of limbs 

 andofopercular 

 fold. Scattered 

 chromatophores 

 on dorsal side 

 of head and an- 

 terior trunk 

 region. 



32 



Twenty 



four day 



larva. 



24 mm 



Operculum 

 growing back- 

 wards. Cement 



organ pro- 

 minent. Acti- 

 vely functional. 

 Chromato- 

 phores scat- 

 tered over 

 whole dorsal 

 surface. 



Hemispheres 



growing for- 



ward but not 



yet reaching an 



terior limit of 



forebrain. 

 Posterior root 

 ganglia devel 

 oped. 



Rudiments 

 of epidermal 

 sense organs 



present. 



(Dermis be- 



ginning to 



appear.) 



Pineal rudiment 

 and paraphysis 

 developed. 

 Hemispheres 

 project beyond 

 the limit of the 

 primary fore- 

 brain. 



Trabe- 

 culae. 

 Mandibu- 

 lar and 

 hyoid 

 arches. 



Para- 

 sphenoid 



Lens still solid 

 thickening of 

 deep layer of 



ectoderm. 

 Slight traces of 



pigment ap- 

 pearing in po- 

 sterior wall of 

 optic cup. 



Endo- 

 lymphatic 

 outgrowth 

 has ap- 

 peared 

 mediodor- 

 sally. Oto- 

 cyst has lost 



its con- 



nexion with 



ectoderm 



Pigment present 

 in hind wall of 

 optic cup. Lens 

 detached from 

 ectoderm. Hind 

 wall thickened. 



Chromato- 

 phores in 

 ectoderm. 



Rods not yet 

 developed. 



Narrow ca- 

 vity has de- 

 veloped. 



With 

 distinct 

 lumen. 

 Curves 

 round tip 

 of in- 

 fundi- 

 bulum. 



Cavity well 

 marked dC' 

 finite closed. 

 Dimple vis' 

 ible on ex' 

 ternal sur- 

 face. 



Outer cells 

 of solid buc- 

 cal rudiment 

 begin totake 

 on an ecto- 

 derm-like 

 character. 



Slit-like 

 aperture 

 along ven- 

 tral side of 

 olfactory 

 organ. 



Solid. Faint 



indications 



of tooth 



germs. 



Lumina in 

 buccal rudi- 

 ment but not 



continuous. 

 Tooth germs 

 well devel- 

 oped. (Ap- 

 pearance of 

 enamel cap.) 



