•92 Annals Eniontological Society of America [Vol. III. 



Expi ANWTiox (TF Plate IX. 

 All figures were drawn with a camera lucida. 



Fig. 1. "Hilar area*" on the slightly more convex side of the egg: op, 

 I'perciilum: ri, rim in which the operculum fits perfectly: m, margin of the 

 "hilar area": -f. semicircular margin: r. buff -colored ridge which passes over 

 into the triangular extension of the black region of the egg; o. micropylar orifice. 



Fig. 2 Vitelline membrane of egg. after the chorion of the "hilar area" 

 has been removed: /. membranous tube, which connects with the opening of 

 the micropylar canal on the inner surface of the chorion. 



Fig. 3. Operculum from the outer surface: in torn so-called 'shell mem- 

 brane" to which the operculum was attached: br. brownish rim of chitin from 

 which the irregularly-flattened chitinous rods arise; c, large, more or less, central 

 space at the top of the operculum enclosed by the anastomosing rods; d, irregu- 

 lar areas which are not constant in number in the different opercula : p, rods 

 which project free into these irregular spaces. 



Fig. 4. Cross section of a part of the operculum: c. brownish upper svirface 

 of the floor of the operculum; a. chitinous deposits, between the floor and top 

 of the operculum, resembling somewhat the thin-walled parenchyma of plant 

 tissue except that no middle lamella is discernible. 



Fig. 5. Cross section of the micropylar canal g, which is surrotuided by 

 extremely thick chitin. This canal opens to the exterior by the micropylar 

 orifice. 



Fig. G. Posterior region of the inner surface of the '"hilar area" of the 

 chorion: i, opening of the micropylar canal in an invagination of the inner 

 surface of the chorion ; c>, micropylar orifice. 



Fig. 7. Vitelline membrane in the region of the micropylar apparatus: 

 V. opening of the membranous tube, the vitelline membrane micropyle. into the 

 vitelline membrane. 



Fig. 8. "Hilar area" on the outer surface of the exochorion; lettering as 

 in Pigs. 1 and 6. 



