It is urged that the imperfect placenta of the bandicoots instead of being vestigial, may be an instance of parallelism, and that in marsupials generally the allantois failed to form a placental connexion.
Finally, there is the hypothesis that marsupials are the descendants of placentals, in which case, as was suggested by its discoverer, the placenta of the bandicoots would be a true vestigial structure.
Alone among marsupials bandicoots have no clavicles.
It burrows in the ground, but in other respects resembles bandicoots in habits.
The opossums of America are marsupials, though not showing anomalies as great as kangaroos and bandicoots (in their feet), and Myrmecobius (in the number of teeth).