Adam and Eve with Abel
Basel, Universitätsbibliothek, A II 1, fol. 19r
(Nicholas de Lyra, Postil to Genesis and Exodus)
The text that this picture illustrates is the first verses of Genesis 4, "And Adam knew Eve his wife: who conceived and brought forth Cain, saying: I have gotten a man through God. And again she brought forth his brother Abel. And Abel was a shepherd, and Cain a husbandman." I am going to go out on a limb and say that the child in the picture is Abel rather than Cain. Abel is the one who is considered a type of Christ in medieval exegesis, and this image seems to adopt the iconography of Madonna and child, with Eve seated and Abel standing on her lap, holding her breast, and placing his face next to hers.
The addition of Abel is an interesting variation on the common images of the post-lapsarian Adam and Eve working at the chores God has assigned to them. Adam is digging with a hoe and Eve holds thread in her left hand from a distaff that rises from between her legs.
More of Abel
More of Adam and Eve
Source: E-codices: Virtual Manuscript Library of Switzerland