Comparison from Alder & Hancock (1845 -1855). Maximum number of lamellae on rhinophores is 19 on A. proxima and 12 on O. muricata but numbers vary with size of slug so numbers overlap. Both have club-shape tubercles but on A. proxima they have a rounded apical point and the greatest circumference is at c. 45% of the height from the base. On O. muricata they are more spherical with a gently rounded or flattened apex and the greatest circumference is c. 66% of the height from the base.