It is, as you say, characteristic, with the final fling at you.
His difficulty about the difference between the two genera of St.Helena Umbellifers is exactly the same as what Nageli has urged in an able pamphlet (207/1.

"Ueber Entstehung und Begriff der naturhist.

Art." "Sitz.

der K.Bayer.Akad.

Der Wiss.