Examining the intestinal tract of a female of Struthio molybdophanes Rchw., died in the Zoological garden at Rotterdam , I found in both the coeca a large number of Nematoids, which I believe to represent a new species, belonging to the genus Sclerostoma Rud. The parasite is characterized as follows: Body cylindrical, transversely striated, slightly narrowed in front, attenuated gradually towards the posterior extremity, with two narrow lateral-membranes. Anterior part of the head surrounded by an annular wall. Buccal capsule with a single row of stiff cilia, surrounding the mouth and a longitudinal furrow along the middle of the dorsal side. The sub-median oral papillae are conical, the lateral ones spade-shaped. Two small, pointed neck-papillae about the middle of the oesophagus. The caudal extremity of the male bent backwards and furnished with a trilobed bursa, consisting of two broad, rather polygonal, lateral lobes and a narrower, pear-shaped dorsal one. Each posterior ray bears at its base two short secondary branches, of which the external is somewhat longer than the internal. The posterior lateral ray (costa posterior externa Schneid.¹)) is rather slender and originates beneath the base of the common stam of the posterior rays; the middle rays are separated, the anterior being larger than the posterior. The anterior lateral ray (costa anterior externa Schneid.) is short and narrow, not much longer than the half of the middle ray; two anterior rays, of which the external is somewhat longer than the internal. Before the cloacal opening of the male there are two large and several small papillae. Two long, slightly S-like bent spicules, measuring 0,87 m.m., with their distal extremity curved kneelike. The caudal extremity of the female terminating in a conical, pointed tail; a large, papillose elevation before the vulva, situated 0,25 m.m. above the point of the tail. A bifurcated vagina, passing into two parallel uterine ducts, directed forwards and terminating each in a long ovarian coecum, with numerous coils.