BY R. BROOM. 
577 
Though the female thus disappointed me in my hope of finding 
accurately the period of incubation, it enabled me to arrive at an 
approximate idea of the period of gestation. The evidence on 
this point would have been more conclusive had the sexes been 
kept apart, but as the male died on the 18th, and was in a very 
low condition for some days previously, impregnation could not well 
have taken place later than the 12th, and as during the period of 
captivity neither appeared to have any interest in the other 
except to use the body of its companion as a stepping stone while 
endeavouring to climb out of the box, it seems highly probable 
that impregnation had taken place when the specimens were 
captured. If this be so, the period of gestation would be about 
26 or 27 days, and even if this were not so, as impregnation could 
not well have taken place later than the 12th, the period of 
gestation could not be less than 18 or 19 days. 
The eggs of my specimen appeared considerably paler than that 
figured by Semon,* being of a light cream colour. The unbroken 
egg measured 14 mm. in its long axis, and about 12*5 mm. across. 
I must express my thanks to Prof. Wilson for having had an 
opportunity of seeing Semon's work. 
Addendum (7th Feb., 1896). — I have recently had an opportunity 
of seeing the person who first observed the two Echidnas referred 
to above— Mr. Angus Mclnnis. He states that the two were 
lying together on a slight hollow at the root of a tree, and so far 
as he could observe front to front, but as on his near approach 
the two separated and endeavoured to escape, he could not be 
certain of their exact positions before being disturbed. He, how- 
ever, assures me that on picking up the male its copulatory organ 
was protruding about a couple of inches; so that there can be 
little or no doubt but coitus had just taken place. This, he 
further states, was on the day previous to my getting them, or 
4th September. This additional information removes the previous 
uncertainty, and enables us to fix the period of gestation at about 
28 days. 
* R. Semon. " Zool. Forsehungsreisen in Australien u.d. Malay. 
Archipel. Band ii.; Monotremen und Marsupialier. " Jena 1894. 
