16 
9 Fairie's garter snakes {E. proxhna) ; born June 28th. 
3 common garter snakes {E. sirtalis); born Jul}^ 19th. 
72 Marcy's garter snakes {E.mardana) ; born June and Sep- 
tember. 
3 Say's pine snakes {Pityophis sayi) ; born October 24th. 
6 ground rattlesnakes {Sistrurus miliarius) ; born August 
30th and September 10th. 
7 water moccasins {Ancistrodon piscivorus) ; born August 23d. 
In ISSO a list was published, giving the proportional 
number of species of mammals which had bred in the Gar- 
dens, to the whole number which had been exhibited up to 
that time. A comparative statement, including the twenty- 
one years which have elapsed since then, is of interest : — 
1880. ' 
1901. 
No. OF Spe- 
Number 
Pkofor- 
No. of Spe- 
Number 
Propor- 
CIFlSKX- 
HIBITED. 
Breeding. 
TION. 
cies EX- 
HIBITED. 
Breeding. 
tion. 
Primates . . 
46 
3 
1 in 15 3 
89 
11 
linS 
Carnivora 
44 
7 
6.1 
92 
18 
5.1 
Insect ivora . 
4 
Chiroptera . 
' 3 
4 
Rodentia . . 
41 
8 
*5.2 
73 
13 
5.6 
Proboscidea . 
2 
2 
Ungulata . . 
4i 
'3.1 
81 
32 
2.5 
Sirenia . . . 
1 
2 
Edentata . . 
4 
8 
^Nlarsupialia . 
19 
' 4 
'4.7 
33 
n" 
' 3 
Monotremata 
1 
• 
201 
35 
5.7 
389 
85 
4.5 
In the remaining classes the proportion of breeding spe- 
cies is much less. Among birds, 19 species have bred out 
of 657 ; of reptiles, 24 out of 263 ; and of batrachians, 2 out 
of 40. 
It would appear that the constant observations which 
have been made in large zoological gardens should have 
thrown light on the nature of the physiological causes 
which underlie the sterility so general among wild animals 
in captivity, but it must be admitted that the advance in 
