The Abbreviationes chronicorum contains De Mirabilibus Britanniae (The Wonders of Britain). The Latin text, with annotations and notes on sources in English can be found in Stubbs* (alternative text).

Note that this set of wonders is likely to be, as is most of the Abbrviationes, a compliation of other sources, including Nennius. There is no discussion of this particular section of the work by Stubbs* in his introductory material, though he does talk more generally about de Diceto's background (Vol.i) and sources (Vol.ii).