gastroacephalus

gas·tro·a·ceph·a·lus

(gas'trō-ă-sef'ă-lŭs),
Unequal conjoined twins in which an acephalous parasite is attached to the abdomen of the autosite. See: conjoined twins.
[gastro- + G. a- priv. + kephalē, head]

gastroacephalus

A rarely used term for unequal conjoined twins in which an acephalic parasite is attached to the abdominal wall of the host twin.