thoracoparacephalus

tho·ra·co·par·a·ceph·a·lus

(thō'ră-kō-par'ă-sef'ă-lŭs),
Unequal conjoined twins in which a rudimentary parasitic head is attached to the thorax of the autosite. See: conjoined twins.
[thoraco- + G. para, beside, + kephalē, head]

thoracoparacephalus

(thō″ră-kō-păr″ă-sĕf′ă-lŭs) [″ + para, beside, + kephale, head]
Thoracopagus twins in which a rudimentary head is attached to the smaller twin.