Nematodes of the superfamily Rhabditoidea are usually free-living; however, a few species appear to be definitely parasitic. The Nematode described in this paper belongs to the latter group. It was found in large numbers in the small intestine of one of two bats, Lasiurus borealis, captured September 15th, 1932, in the vicinity of Washington, D.C. Additional specimens of this species of bat were not obtained for examination. Two specimens of each of two other species of bats, Eptesicus fuscus and Nycticeius humeralis, collected from the same locality were negative for this parasite. The Nematode is a member of the family Cylindrogasteridae Chitwood 1933, and appears to be congeneric with Longibucca vivipara Chitwood 1933, found in the wall of the stomach of a South American snake, Pseudoboa cloelia.