Right-hand figure, under side of part of the wing-nervure, much magnified, showing the teeth, st.
"The Descent of Man and Selection in Relation to Sex, Vol. I (1st edition)"
Charles Darwin
Left-hand figure, upper surface of wing-cover, with the projecting, smooth nervure, r.
"The Descent of Man and Selection in Relation to Sex, Vol. I (1st edition)"
Charles Darwin