1. Genus of nonphotosynthetic, nonfruiting, gram-negative, chemoorganotrophic, gliding bacteria that exist as multicellular filaments with the long axis of individual cells perpendicular to the long axis of the filament. The cells are flattened and curved to yield a convex-concave, crescentic symmetry. Isolated from the oral cavity of mammals. Type species is Simonsiella muelleri.