“IJ 
DEVELOPMENT OF THE OPOSSUM 
TABLE 1 
Summary of eggs 
Nn 4 f 
i=] ia] ° 
B ae 3 
| 3 Zoo | Bi 
{Vee mor) ||| 8 
= NUMBER OF NORMAL 5 A = 
RAS 4 =) 
2 EGGS = A < z 
& BNE n 
es] me & Ho 
2 sino co) 
Dp 5A 5 =] 
a a I 
A. Previously reported: litters Nos. 21 to 144, 21 different animals 
1, From pregnant animals............... 35 248 130 | 378 
2. From pseudopregnant animals........ 2 0 37 37 
B. New material: litters Nos. 173 to 415, 45 different animals 
3. From pregnant animals at first opera- 
Grone (eftuberus)) ss sce ces eerie: ole 22 166 97 263 
(63% normal) 
4. From second operation (right uterus) 
eggs used for this article............ 14 107 79 | 186 
; (57.5% normal) 
5. Later stages mentioned in summary, 
Secondeoperatlomeemsaeeeiers ss caer 16 137 39 | 176 
(78.4% normal) 
6. From pregnant animals, proportion es- 
Cin abe Cheeta no er OAR Aer on Ge 2 os ie 16 120 62 | 182 
(Estimated) 
7. From pseudopregnant animals........ 15 0 156 | 156 
Motaleitemshleeoe 4snanduOwenne sea sees | Lod 641 368 |1009 
(63.6% normal) 
Total mentioned in summary.......... 120 778 600 |1378 
are abstracted from the writer’s previous study (Hartman, ’16), 
to which the reader is referred for further details. 
In the system which I have employed for the identification 
of the specimens each animal receives a number, and the litters 
of eggs taken from that animal receive the same number. With- 
out further designation, a number may represent all of the eggs 
secured from both uteri when the animal is merely killed and 
both uteri removed simultaneously; but when the animal was 
used for two stages, the simple number represents the first batch 
