Normal Plates of the Development of Lepidosiren paradoxa and Protopterus annectens. 



25 



Teeth 



Digestive 

 tract and 



Pancreas 



Visceral 

 clefts 



Thyroid 



Post- 



branchial 



bodies 



Thymus 



Lung 



Urogenital 

 System 



Heart 



and 



vessels 



Myo- 

 tomes 



Splanchno- 

 coele 



Stage 



Endoderm 



solid ex- 

 cept in 



region of 



cloaca. 

 Liver rudi- 

 mentgrow- 



ing for- 

 wards be- 

 neath peri- 



cardium. 



Tooth 



gernis 



with cal- 



careous 



matter. 



Liver rudi- 

 ment with 

 fine yolk. 



Round yolky 

 projection 

 containing 



small lumen 

 in its centre. 



Attached to 



gut dorsally 



by narrow 



stalk at level 



of hinder pro- 



nephrostome 

 to left of me- 

 sial plane and 

 projecting to- 



wards right. 



Dorsal pan- 



creatic rudi- 



ment with 



thick yolky 



wall and large 



definite 



cavity. 



Ventral rudi- 



ments solid. 



All solid. 



Solid 

 yolky 

 rudi- 

 ment. 



Heavily yol- 

 ked solid 

 rudiment 



arising from 



floor of 



pharynx, 



stretching 



from root of 



cleft VI for- 

 wards to 

 cleft V on 

 left side. 



Solid. 



(Connec- 



tion with 

 pharynx 

 reduced 



to slender 

 cord or 

 broken 



through.) 



Bodies of 



teeth 



well 



devel- 



oped. 



Pharyn- 

 geal lumen 



not yet 

 contmuous 

 in front of 

 glottis. Be- 

 hind glottis 

 for some 

 distance 

 nearly so- 

 lid. Liver 

 with rieh 

 vascular 

 network. 

 Wide bile 

 duct. 



Pancreas 

 compact 

 penetrated 

 by vascu- 

 lar network, 

 undergoing 

 histological 

 differentiation 

 Three rudi- 

 ments fused 

 together. 



Cleft I solid 

 except for 



PiNKUS' 



organ. Re 

 moved from 

 skin. Still in 

 connection 



with 

 pharynx. II 

 and III open, 



IV nearly 

 perforate; V 

 and VI solid. 



Isolated, 

 vascular. 



Still solid, 

 yolky, con- 

 nected with 

 pharynx bya 

 narrow neck. 

 Projects for- 

 wards and 

 downwards 



from is 



attachment, 



in contact 



with hind 



wallofaortic 



arch VI. 



No longer 

 yolky. Pene- 

 trated by 

 blood 

 vessels. 



Buds pre- 

 sent at 

 dorsal 

 ends of 

 clefts II 

 and (lar- 

 ger) ni. 



Rounded 



projection 



from mid 



ventral sur- 



face of 



pharynx 



Stretches 



back along- 



side oeso- 



phageal 



rudiment: 



small closed 



cavity for- 



med by cyto- 



lysis in 



centre. 



No bilobing. 



Wide lumen 

 but no glot- 

 tis pharynx 

 being solid 

 at this level. 

 (Lung rudi- 

 ment 

 distinctly bi- 



lobed, ex 

 tendingback 



short 



distance be- 



hind pO' 



sterior 



nephro- 



stome.) 



Glottis open 

 Lungs with 

 thin vascular 

 wallsextend 



ing back 



nearly half 



the distance 



from glottis 



to cloaca 



Meson ephric 

 ments. 



rudi- 



(Archinephric 



ducts much coiled 



anteriorly. About 



12 mesonephric 



rudiments.) 



Vitelline 

 network 

 of vessels 

 over sur- 

 face of 

 yolk. 

 (Right 

 posterior 

 cardinal 

 1 arger 

 than left 

 in front. 

 Right and 

 len con- 

 nected by 



cross 

 Channels.) 



(Right 



posterior 



Cardinal 



larger 



and ana- 



stomo- 



sing with 



left.) 



Pronephric cham- 

 ber posterior to 

 main mass of pro- 

 nephriccoils. Much 

 connective tissue 

 between coils: also 



in glomerulus. 

 Nephrostomes still 

 open with flagella 

 though walls de- 

 generating. An- 

 terior nephrostome 



opens mto pro- 

 nephric Chamber at 

 extreme front end. 

 Posterior back near 

 hind end of glome- 

 rulus. (Archi- 

 nephric ducts unite 

 close to opening 

 into cloaca.) 



Myo- 

 tomes 

 have not 

 yet met 

 ventrally 

 in trunk 



Teeth 

 project 

 into buc 

 cal cavity 

 but are 

 covered 

 by epi- 

 thelial 

 sheath. 



II— V per- 

 forate (IV 

 barely per- 

 forate). 

 Illverywide. 

 PiNKUs' Or- 

 gan isolated 

 from 

 pharynx. 



Thyroid 



isolated 



secreting. 



Open 



sponge work 



with blood 



vessels in 



meshes. 



Pancreas 

 much larger 

 lying in dorsal 

 groove of gut 

 Forms mass of 

 branched sec- 

 retory tubes 



with fine 

 lumen, separ- 

 ated by con- 

 spicuous con- 

 nective tissue 



containing 

 blood vessels, 



Normentafeln zur Kntwicklungsgeschichte der Wirbeltiere. X. 



Bud from 

 cleft II 

 small. 

 That of 

 UI much 

 enlarged. 



Extend back 



rather more 



than half 



way to 



cloaca. 



Peri- 



cardiac 



coelom 



isolated 



from 



main 



splanch- 



nocoele 



and from 



pro- 

 nephric 

 Chamber. 



XXXII 



XXXIV 



Peri- 



cardiac 

 coelom 

 isolated 

 from 

 main 

 splanch- 

 nocoele 

 and from 

 pro- 

 nephric 

 Chamber. 



XXXV 



XXXVI 



