226 Venous System of Didelphys Marsupialis (1) 
Prate TT. 
Figures 37-44. 
Figs. 37 (section 244) and 388 (section 253). Transverse sections of an 
8 mm. embryo of Didelphys, Series VIII. 
Fie. 39. Transverse section of an 8 mm. embryo of Didelphys, Series X, 
incomplete. 
Fics. 40 (section 384) and 41 (section 389). Transverse sections of an 
8 mm. embryo of Didelphys, Series IX. 
Fic. 42. Transverse section of an 8 mm. embryo of Didelphys, Series III, 
incomplete. 
Fics. 43 (section 293) and 44 (section 350). Harvard Embryological Col- 
lection, Series No. 614. Transverse sections of a 10.5 mm. pouch young of 
Didelphys. 
PLATE IV. 
Figures 45-52. 
Figs. 45 (section 368), 46 (section 505), 47 (section 520) and 48 (section 
521). Harvard Embryological Collection, Series No. 614. Transverse sections 
of a 10.5 mm. pouch young of Didelphys. 
Fics. 49 (section 244), 50 (section 214), 51 (section 199) and 52 (section 
197). Harvard Embryological Collection, Series No. 617. Frontal sections of 
a 11.5 mm. pouch young of Didelphys. 
PLATE V. 
Figures 53-61. 
Fies. 53 (section 635), 54 (section 750), 55 (section 772) and 56 (section 
789). Transverse sections of 11.5-12 mm. embryo of Didelphys, Series II. 
Fic. 57. Transverse section of a 14 mm. pouch young of Didelphys, 
Series IV. 
Fic. 58. Transverse section of a 15 mm. pouch young of Didelphys, 
Series XII. ; 
Fic. 59 (section 442). Transverse section of a 15 mm. pouch young of 
Didelphys. Series VII. 
Fic. 60. Transverse section of a 15 mm. pouch young of Didelphys, Series 
IX. 
Fic. 61 (section 448). Transverse section of a 15 mm. pouch young of 
Didelphys. Series VII. 
