Two species, including a new one of Gastrothylaxand two species of Carmyeriusfrom ruminants in the Philippines, are identified, described and illustrated based on present materials. These are Gastrothyalxcrumenifer, Gastrothylaxcaraphilensisnew species, Carmyeriusgregariusand Carmyeriussynethes. The histo-morphology of their muscular organs as seen in median sagittal sections is detailed. Gastrothylaxcaraphilensisis characterized by its small size, ceca extending to the level of the posterior border of the testes or beyond them; pharynx of the paramphistomum type, acetabulum of the carmyerius type, terminal genitalium of the bubalis type in median sagittal section; ventral pouch roughly triangular in cross section with the apex directed dorsally. It is differentiated from two other valid species of the genus namely G. crumeniferand G. compressus. Gastrothylaxglandiformis, G. indicus, G. globoformis, G. zhonghuaensis and G. boyangensiswere inadequately described in literature and features of their muscular organs are not known. Until new specimens are examined for these features as seen in median sagittal sections, they are considered species inquirendae. The value of employing the shape or outline of the ventral pouch as seen in cross section in combination with other characteristics in separating species of the pouched amphistomes is discussed.