Caenolestinae of the classification most commonly used for the last 70 years would have to be replaced by Abderitidae and Garzoninae. This usage would upset continuity and stability in nomenclature of this diverse and important group of South American mammals.In view of this, Marshall & Tedford (1978, p. 58) submitted an application to the Commission to safeguard the family-group names Caenolestidae Trouessart, 1898, and Palaeothentidae (Sinclair, 1906) Osgood, 1921 , from the threat to their stability represented by the prior names Abderitidae Ameghino, 1889, Epanorthidae Ameghino, 1889, Garzonidae Ameghino, 1891b, and Decastidae Ameghino, 1893b. They asked the Commission:(1) to use its plenary powers to rule that the family-group names Abderitidae Ameghino, 1889, Garzonidae Ameghino, 1891b, and Decastidae Ameghino, 1893b, not be given nomenclatural precedence over the family-group names Caenolestidae Trouessart, 1898, and Palaeothentinae Sinclair, 1906;(2) to place the following family-group names on the Official List of Family-Group Names in Zoology with the endorsements that:(a) Caenolestidae Trouessart, 1898, be given nomenclatural precedence over Abderitidae Ameghino, 1889, Garzonidae Ameghino, 1891b, and Decastidae Ameghino, 1893b;