This remarkable specimen, which has puzzled every entomologist who has seen it, was bred by M. Alfred Wailly from a cocoon received from some part of North America. It may be a hybrid between S. cecropia and some other species, but if so, it is so different from all the other known species, that it is difficult to guess with what it could have been crossed. It is equally difficult to imagine that it is a new species. The specimen is a female, and equals the largest specimens of S. cecropia in size, measuring fully 6¾ inches in expanse; and the wings are more rounded and less oblique than in cecropia. The body resembles that of cecropia, except that the abdomen is banded with yellowish gray and black. The base of the fore wings is brown, thickly scaled with white towards the costa; below this is a brick-red blotch, longer and narrower than in cecropia. Beyond this is a white space, extending nearly from the base to one third of the length of the wing on the inner margin, but curving up to the costa in a rather narrow stripe.