Ordovician and Silurian trilobite faunas of the White Head Formation, Perce region, Quebec

Distinctive trilobite faunas of Ordovician and Silurian age can be recognized. An Upper Caradoc fauna is based on graptolites. Two Lower or Middle Ashgill trilobite faunas can be separated: a lower Stenopareia and an upper Remipyga fauna. An Upper Ashgill, or Dalmanitina fauna, is reported for the first time in the New World. Silurian fossils, recognized for the first time in the White Head, can be divided into a Lower Llandovery and an undifferentiated (no younger than middle Upper) Llandovery fauna. Classification of the Phacopidae is reviewed; Phacopidella is removed from the family, and Eophacops is considered a junior synonym of Denckmannites. Two new genera and species are described: Murphycops skidmorei (Phacopinae), and Portaginus robustus (Illaenacea) as the type of a new family, Portaginidae.