Zoogeography of the echiuran fauna of the East Pacific Ocean (Phylum: Echiura) Author Biseswar, Ramlall text Zootaxa 2012 3479 69 76 journal article 10.5281/zenodo.282351 b91f67d2-9672-4546-bc03-a70a0c4422fe 1175-5326 282351 D097E1C5-37F3-45F7-8022-3C063B2A667D Thalassema steinbecki Fisher, 1946 Description. Proboscis as long as trunk, broad proximally but ribbon-like distally. Trunk small, slightly translucent. Gonoducts two pairs, gonostome with simple subcircular opening. Interbasal muscle well developed, passing through loop of neuro-intestinal vessel. Anal vesicles as long as trunk covered with numerous ciliated funnels.