Mark. — Lepidosteus. 



ABBREVIATIONS. 



cap. Head of villus. pd. Stalk of villus. 



c.-t. cp. Connective-tissue corpuscle, rx. Root of villus. 



fus. mat. Maturation spindle. st. vil. Villous layer of egg meniDrane. 



gran. Granulosa. th.fol. Membrana propria of tlieca folliculi 



m py. can. Micropylar canal. vac. Vacuole. 



m py. cl. Micropylar cell. vit. Vitellus. 



nl. Nucleus. vs. g. Germinative vesicle. 



nl. gran. Nucleus of granulosa cell. z. r. Zona radiata. 



PLATE VI. 



All figures on this plate are magnified 515 diameters. 

 Fig. 1. Radial section through the micropylar canal, somewhat oblique to its 

 axis. The egg was preserved in 5 per cent potassic bichromate and 

 stained in carminic acid dissolved in 80 per cent alcohol. 



" 2-4. Three successive tangential sections through the bottom of the micro- 

 pylar funnel and the micropylar canal of an egg stripped from the 

 fish preserved in 90 per cent alcohol, and stained in alcoholic borax- 

 carmine. The zona radiata is closely enveloped by the yolk. 



" 5-8. Tangential sections through the deeper portions of the micropylar funnel 

 of an ovarian egg hardened in 0.25 per cent chromic acid and stained 

 in alcoholic borax-carmine. In Figures 5 and 6 the sections pass 

 through the deep portion of the zona radiata which is not infolded to 

 form the funnel, but in Figures 7 and 8 only that portion of the zona 

 is cut which projects as a conical elevation into the substance of the 

 yolk. Only alternate sections were drawn. 



