Oesophagostommum (Proteracrum) columbianum
Fig.1 :  Anterior end, showing corona radiatae, cervical groove, and a pair of cervical papillae
Fig.2 : Posterior end of male, showing spicules, a pair of prebursal papillae and arrangement of rays in bursa
Fig.3 : Posterior region of female, showing opening of vulva and anus
Fig.4 :  Egg