Coluber radiatus and C. melanurus — Bergman 
145 
Body 
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COLUBER RADIATUS 
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FlG. 1 . Body lengths, male and female specimens. 
them out, because, in any event, the point of 
intersection between the first steep part of the 
curve and the plateau is to be found at a length 
of about 950 mm. The curve does not suggest 
a sexual dimorphism in body length. 
SEX RATIO: It is always a difficult question 
whether the findings on a small group can be 
used in a more general way. In the case of the 
sex ratio in C. radiatus, there are three inde- 
pendent observations, each one on a small group, 
but all pointing in the same direction. In Table 
2 the figures of Kopstein (1938) and those of 
our material from Surabaia and Djakarta are 
shown. 
These figures are very suggestive of a sex 
ratio of two males to one female. However, in 
1941 Kopstein published a list of measurements 
on 16 males and 15 females, those of 1938 in- 
cluded. This may signify that a few years more 
of collecting can change the first impression. 
On the other hand Kopstein, when collecting, 
has not included in his method the factor of 
TABLE 1 
Coluber radiatus, LENGTH OF BODY AND OF TAIL 
author 
MALES 
FEMALES 
SEX 
UNKNOWN 
Body 
Tail 
Body 
I Tail 
Body 
Tail 
de Rooy 
Smith 
1520 
1267 
1380 
370 
(293)* 
(311) 
1445 
1218 
1352 
350 
(308) 
308 
1280 
330 
Kopstein 
Bergman 
* The figures for the length of the tail in parentheses do not 
refer to the animal whose body length is given. 
TABLE 2 
Coluber radiatus, Sex RATIO 
AUTHOR 
MALES 
FE- 
MALES 
TOTAL 
Kopstein 1938 
9 
6 
15 
Bergman Surabaia 
9 
5 
14 
Bergman Djakarta . 
20 
8 
28 
Totals 
38 
19 
57 
not-selecting as a conditio sine qua non, and it 
seems probable that his first figure is more the 
result of a random sample than the second one. 
But even when we take Kopstein’s later figures, 
there is a greater number of males, still in the 
order of two males to one female. 
MATURITY: In our small series, the shortest 
female carrying growing eggs (which are 6 mm. 
in length) has a body length of 1006 mm. As 
we saw in the curve of successive body lengths 
( Fig. 1 ) , the intersection of the ascent and the 
plateau is at about 950 mm. body length. We 
will not be very far from the real value when 
we take this figure as the lower limit of the 
adult size for both sexes. 
BODY LENGTH: When all animals are taken 
together, the average figure for the length of 
the body is 1096 mm. in males, 898 mm. in 
females. However, we have already noted that 
there is an excess of five new-born animals in 
the female group, which, in a total of 28 ani- 
mals, makes the average figure too low. If these 
five females are removed from the series, the 
average length for the females would be 1018 
mm. Taking the adults alone (in this case the 
animals with a body length longer than 950 
mm.), the average length for 38 males is close 
to 1170 mm., and for 16 females is 1178 mm., 
which is practically the same figure. It can be 
TABLE 3 
Coluber radiatus, MUTILATION OF THE Tail 
TAIL 
Whole 
Mutilated 
Totals 
Males 
35 
10 
45 
Females 
24 
4 
28 
Total 
59 
14 
73 
