Originally monospecific this family now comprises three described species. The body form is long and slender raised in profile with a notal edge that is completely absent and an underlying foot that is wider. They grow to 20 mm crawling length and have a very similar appearance to the Flabellinidae. The cerata are arranged in separate clusters upon elongated elevations arranged down the lateral sides of the notum and may number from four to twelve. Each ceras carries a digestive gland branch that continues to the tip ending in a cnidosac containing nematocysts from their prey. The digestive gland most often fills or almost fills the internal space of the ceras and the cnidosac is elongated. The rhinophores are smooth and the same size or shorter than the oral tentacles. The eye spots are positioned at the base of each rhinophore. Oral tentacles are always of a distinctive length, smooth and tapered in appearance. Anterior foot corners are present as moderate to long curved tentacles (propodial tentacles). The tail is flat moderately long and gradually tapers. There are no separate gill structures with gaseous exchange taking place through the thin walls of the body and cerata. They feed upon hydroids.