One of these branches communicates with the afferent lophophoral vessel, while the other one opens into the crescentic efferent lophophoral vessel (r.v.).
Dorsal or afferent vessel.
The principal blood-channels are two longitudinal vessels which run down the entire length of the body, and are known as the " afferent " vessel (af) and the " efferent " vessel (ef) respectively, from their relation to the tentacles.
According to researches in 1907 by De Selys-Longchamps, the blood is driven by the afferent vessel (af) to a crescentic lophophoral vessel (d.v.) which supplies the tentacles.