APPENDIX. 



Table op Comparison of the Organisation of the Embryos of 



Stages C — E. 



p. nasuta, Stage C. 



7 ram. 

 from crown to rump. 



Form of 

 body 



Limbs 



Marked cervical flex- 

 ure. Facial region 

 definitely estab- 

 lished. External 

 nares formed. Dis- 

 tinct hyoinaiidibu- 

 lar orroove and 

 precervical sinus 

 (Fig. 6). 



In fore-limb, 5 digits 

 indicated, the 3rd 

 the largest. Hind 

 limb still a flattened 

 bud. In both, plan- 

 tar surface still di- 

 rected mesially. 



P. obesula, Stage D. 



875 ram. 



from crown to rump. 



Notochord Notochordunconstric- 

 and ted, invested by a 



vertebral continuous mesen- 

 column chymatous sheath. 



Head still strongly 

 bent, neck protu- 

 berance prominent. 

 External auditory 

 meatus and trian- 

 gular ear pinna. 

 Snout now more 

 marked. Precervi 

 cal sinus closed. 



In the fore-limb the 

 5 digits are now 

 distinct, 1st and 5th 

 quite small, 3rd the 

 largest. Limb now 

 flexed at the elbow. 

 Plantar surface di- 

 rected somewhat 

 dorsally. Digits of 

 hind limb still 

 united, paddle-like, 

 plantar surface me- 

 sially directed. 



Cartilaginous centra 

 and neural arches 

 laid down. 



P. nasuta, new-born. 



Stage E. 



14 mm. crown to rump. 



Head length 6 mm. 



Head raised but bent 

 at right angles with 

 trunk. Lips fused 

 to form " Saug- 

 mund." Prominent 

 snout. Positions of 

 eyes and ear pinnae 

 just recognisable, 

 covered by epitri- 

 chium. Remains of 

 allantoic stalk at 

 navel (Fig. 36). 



In fore-limb slender 

 recurved claws on 

 2nd, 3rd, and 4th 

 digits, the third 

 digit the largest. 

 In hind limb digits 

 all indicated, but 

 not free from each 

 other; the 4th the 

 largest. 



Marked cartilaginous 

 centra with trans- 

 verse processes and 

 neural arches, the 

 latter not yet united 

 above spinal cord. 



