80 J. W. JKNKINSON. 



26. Robinson, A. — "Observations upon the Uevelopniont of the Common 



Ferret, Mustela ferox," ' Anat. Anz.,' viii. 



27. Selenka, E. — ' Keimbliitter und Primitivorgane dcr Maus,' Wiesbaden, 



1883. 



28. Selenka, E. — ' Die Blatter umkehrung im Ei der Nagetliiere,' Wiesbaden, 



1884. 



29. Selenka, E. — 'Das Opossum,' Wiesbaden, 1886-7. 



30. Selenka, E. — ' Studien iiber Entwickelmigsgeschichte der Tliiere,' 



funftes Heft, zweite Hiilfte : " Keimbihlung des Kalong (Pteropus 

 edulis)," Wiesbaden, 1892. 



31. ViRCHOW, H. — 'Dottersyncytium, Keimhautrand, und Bezieimngen zur 



Koukrescenzlelire,' ' Ergebnisse der Anatoniie und Entwickelungs- 

 geschiehte,' 1896. 



DESCEIPTION OF PLATES 5 & 6, 



Illustrating Mr. J. W. Jenkinson's paper on " A Re-investiga- 

 tion of the Early Stages of the Development of the Mouse.^' 



PLATE 5. 

 (The dark is hypoblast, the light epiblast.) 



Figs. A~D. — Diagrams to illustrate Robinson's account of the develop- 

 ment of the mouse. 



In A the blastula is shown, with a thin-walled epiblastic roof and a thick 

 hy])oblastic floor. In B and C the roof has been invaginated to form the 

 epiblastic knob, covered by the trophoblast, and the cavity of the yolk-sac has 

 arisen by vacuolation of the floor. In D the trophoblastic Trager has 

 invaginated the epiblastic knob into the yolk-sac. 



Figs, E — G. — Diagrams to illustrate Duval's theory of the origin of the 

 epiblastic (amniotic) mass. F is the hypothetical " stade didermique pri- 

 milif." In G the amniotic mass is produced by the proliferation of the outer 

 layer. 



Fig. H. — Diagram to illustrate Robinson's theory of the partial over- 

 growth of the epiblastic trophoblast over a closed hypoblastic vesicle. 



Figs. I, K. — Diagrams to illustrate Minot's comparison of the mammalian 

 blastocyst, K, with the frog's blastula, I. In K the hypoblast has decreased 

 in size through loss of yolk, and has grown over the epiblast as Rauber's 

 layer. 



Figs. L — 0, — Diagrams to iUustrate Assheton's hypothesis of the hypo- 



