This catalogue described the English language portion of the Kelly Irish Manuscripts Collection. This portion mainly comprises transcribed and translated Irish legends and histories copied by Denis Henry Kelly and Michael McDermott, in particular prose and metrical translations by Kelly of Fenian (or Ossianic) Tales (English MSS 479-494) (transcriptions by Michael McDermott of the uncontracted Irish text can be found at Irish MSS 45-50, other manuscripts of Fenian Tales in Irish can be found at Irish MSS 61-62, 68, 115). The other substantial group within the collection is the four volume Collectanea De Rebus Hibernicis (English MSS 496-499), containing a mixture of transcribed historical accounts, letters, treatises and legends. In addition there are transcriptions and translations by John O'Donovan and Kelly of various Irish manuscripts and letters, including the Annals of Inisfallen (English MS 478) and the Macariae Excidium (English MS 500), and a small quantity of original Irish manuscripts in English.
The collection as a whole contains works of history, literature, genealogy, heraldry, mythology and grammar, predominantly in the form of Irish transcriptions, some with English translations, and a small number of early manuscripts. The collection bears witness to an important phase of Ireland's Cultural Revival, when middle-class scholars began to disseminate information gleaned from study of early Irish manuscripts to a wider audience.
A brief summary of the remainder of the Collection follows:
- Transcriptions of literary and historical manuscripts in Irish, many with translations into English and notes. Most of these manuscripts were written by D.H. Kelly, but a significant number were written by his friends, in particular Eugene O'Curry, John O'Donovan, W.M. Hennessey, Michael McDermott and Joseph Longan;
- Extracts from the Ordnance Survey papers in the library of the Royal Irish Academy relating to Sligo, Mayo, Clare, Galway and Roscommon, transcribed by D.H. Kelly;
- Grammars and notes on Irish language and transcriptions, and manuscript copies of catalogues of Irish manuscripts in the Royal Irish Academy, Trinity College Dublin and the British Museum;
- Original letters from Eugene O'Curry and John O'Donovan to Kelly, 1837-1861 (Irish MS 20);
- Original Irish language manuscripts collected by D.H. Kelly, including the Hanrahan Collection of Fenian Tales;
- Small number of eighteenth-century manuscripts which belonged to Count Charles O'Kelly (English, French and Latin);
- A number of genealogical manuscripts, pedigrees and armorials etc. of Irish families (Irish, English, French and Latin).