Stromatoporoids are found in all five members of the Manlius Formation of New York and are abundant at many localities. The fauna is dominated by two closely related species, Habrostroma microporum (Girty) and H. centrotum (Girty). Present in lesser numbers are Intexodictyon manliusense n. sp., Plectostroma micum (Bogoyavlenskaya), Actinostromella vaiverensis Nestor, Densastroma pexisum (Yavorsky), Habrostroma cf. H. centrotum (Girty), and ?Parallelostroma sp. The assemblage displays both Silurian and Devonian affinities.