Solitary zooids: up to 50 mm long (Ritteriella amboinensis). Number of body muscles varying from 9 to 12. MI to MIII or MI to MIV continuous ventrally. All oral muscles continuous ventrally. Oral retractor not reaching MI. Intestine loosely coiled. Blood-forming organ bean-shaped.
Aggregate zooids: up to 30 mm long, excluding projections (Ritteriella amboinensis 1). Number of muscular fibers (MI-MVI): 31-47.