;]70 HTUOTA: OX TTIE SERO-A MXIO'I'TC < 'ONXKCTT* )X, 



Explanations of Abbreviations and Colours 

 used in Figures. 



By tlio >i\de of every ti^'iivo. tlio ago of tlie ombrvo, and the scale of eiilavgcinent 

 ave given. XitincrdJ.s in smull ii//>i: on some of tlie surface views sliow tJie levels of 

 the sections, represented in fignres wliicli ave niarl^ed with the coi'i'esponding nuniher. 

 Abbreviations used in the plates are : — 



Alb for Albumen, 



All „ Allantois, 



All. Vein „ Allantoic Vein, 



Aiun „ Amnion, 



Coel.' „ Extra-Embryonic Coelomic Cavity, 



Inall. Sep ,, Literal Ian toic Septum, 



L. All. Art , „ Left Allantoic Artery, 



Proam „ Proamnion, 



11. AIL Art ,, Plight Allantoic Artery, 



S. A. C ,, Sero-Amuiotic Comiection, 



Ser. Env ,, Serous Envelope, 



Hcil represents in the surface views (Figs. 1-5G) arteries — those of the inner 

 allantoic limb being formed of dotted lines — and the purely mesoblastic part of the 

 sero-amniotic connection. In the figures of sections (Figs. 57-94) red represents the 

 protoplasma of mesoblastic cells: 



Blue represents veins — those of the inner allantoic limb being in dotted lines. 

 Blue also represents albumen in Figs. 51-5(i, und the liypoblast in the tigures of 

 sections (Figs. 57-94). 



Black represents in the surface views (Figs. 1-5G) the epiblastie bridge of the 

 sero-amniotic connection, and in tlie figures of sections (Figs. 57-94) the nuclei 

 of cells. 



Grei/ represents the interallantoic septa (Figs. 15-20). In the figures of sections 

 it represents the epiblast. 



Yelloir represents yolk in Figs. 17-18. 



(rreen represents tiie outer surface of the outer allantoic limb. 



