4 
Transactions of the Boyal Society of South Africa. 
very unlike my reconstructions. Luther (' Z. wiss. Zoo.,' v. 77, p. 235), how- 
ever, is of opinion that Bohmig's lateral receptaculum is an artefact. Even 
if this is so, the relative thickness of the ovary and oviduct still presents a 
difference which is striking when it is borne in mind that the oviduct is not 
a hollow organ and therefore not capable of much expansion. M. mutabile 
is also described as possessing a bursa copulatrix, which is very considerably 
larger than the vesicula seminalis ; a comparison of my Figs. 1 and 2 will, 
however, show that the size of these organs differs according to the amount 
of seminal fluid which they contain. 
Conclusion. — M. antarcticum shows an almost negligible amount of varia- 
tion from M. mutabile from Tierra del Fuego ; whether this similarity is due 
to parallel evolution or to a former land connection or to dispersal by birds 
must remain an open question, although it is noteworthy that the nearest 
approximation to these two species is M. canum from S.W. Australia. 
