Thus, in Amur-land and North America there occur species of _Smerinthus_ which closely resemble our _Ocellatus_ in colour, marking, and form of wing, and which possess the characteristic large blue ocellus on the hind-wings. _S. Excæcatus_ is quite correctly regarded as the representative American form of our _Ocellatus_, but its caterpillar, instead of being leaf-green, is of a chrome-yellow, and possesses dark green instead of white oblique stripes, and has moreover a number of red spots, and a red band on the head--in brief, in the very characters (colour and certain of the markings) in which the imagines completely agree it is widely different from _Ocellatus_. It appears also to be covered with short bristles, judging from Abbot and Smith’s figure.[191] Just in the same way that the species having the nearest conceivable form-relationship to _Ocellatus_ possesses a relatively strongly diverging larva, so does the nearest form-relation of _Populi_ (imago) offer a parallel case. This species, which is also North American, lives on _Juglans Alba_. The imago of _Smerinthus Juglandis_ differs considerably from _S. Populi_ in the form of the wings, but it resembles the European species so closely in marking and colouring that no doubt can exist as to the near relationship of the two forms. The caterpillar of _S. Juglandis_,[192] however, differs to a great extent from that of _Populi_ in colour--it is not possible to confound these two larvæ; but those of _Populi_ and _Ocellatus_ are not only easily mistaken for one another, but are distinguished with difficulty even by experts.