Wijnhoff, 1913
Palaeonemerteans with two principal body wall muscle layers (outer circular, inner longitudinal), but with an incompletely developed inner circular stratum in the foregut region; cerebral ganglia and lateral nerve cords situated in body wall longitudinal muscle layer; nervous system with neither neurochords nor neurochord cells; proboscis with outer circular and inner longitudinal muscle layers; blood vascular system consisting of paired lateral longitudinal vessels tranversely connected only by cephalic and anal lacunae, without a mid-dorsal vessel; cerebral sensory organs absent; some species with two minute eyes, others eyeless; mouth either far behind cerebral ganglia or not widely separated from them; longitudinal muscle plate present immediately adjacent to dorsal foregut wall; foregut with circular splanchnic muscle layer; cephalic region with four large nerves; sexes separate.
Source: Gibson, 1982.
The following species of this genus occurs in the region:
Procephalothrix filiformis