The head you see is that of the baby, being nursed in the 'pouch' formed by the patagium or skin membrane stretching from head to tail.The mother 'flew', or glided, with her baby attached underneath.
Die Sugthiere in Abbildungen nach der Natur /.Erlangen :Expedition des Schreber'schen sugthier- und des Esper'schen Schmetterlingswerkes [etc.,1774]-1846..biodiversitylibrary.org/page/31078262
