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 organisms or an active struggle of these adults with any other organism. The inquiline usually reaches maturity and emerges from the gall, enjoying its first moment of a free or active life, some time after the brief adult life of the gall-wasp has been completed; often the inquiline does not appear until a half-year after the death of the gall-wasp. Since there is no meeting of the two adults and since there are practically no enemies of the adults of either species—nor could either adult offer any sort of resistance to an enemy, beyond that afforded by minute size, rapid running, or very feeble flight—it is hard to conceive of any advantage gained by the mimicry, and consequently hard to believe that natural selection has had any place in effecting the similarity. Nor is it possible that each species of inquiline has originated separately from its host species, for the differences, as pointed out, are largely generic or family characters.

I wish to note, without comment, that the larvæ of inquilines and hosts live in closely identical environments. Though the two do not usually come into actual contact and do not interfere in any way with each other, they do spend all but the very later part of their lives within a millimeter or less of each other and subsist most likely on the same sort of food—plant-cell contents, mainly sugars, or whatever it may be, supplied by the same individual plant and in the very confined and specialized part. of that plant, the gall.

It has seemed worth noting this much, although I have not yet accumulated data enough to warrant generalizations. It would seem that with this group of insects there are conditions especially favorable for obtaining, by further observation and possibly through experiment, interesting evidence as to some factors producing some sorts of mimicry.

Andricus furnaceus, new species Plate XXII, Figures 14 to 16

—Head, thorax, legs, and antennæ reddish to dark piceous, abdomen reddish yellow; mesonotum deeply reticulate, entire thorax and legs covered with whitish hairs; cubitus not reaching the basal vein. reddish, shading to piceous or black on the face, irregularly rugose and rather sparsely covered with yellowish hairs; head broadened behind the eyes, with the cheeks broad; antennæ uniformly reddish brown to reddish piceous, 14-jointed, the first joint broadly obconical, the third not much longer than the fourth, the following joints gradually shorter, the fourteenth joint one-third longer than the thirteenth. dark reddish piceous, almost black on the scutellum, reddish piceous to black on the pleuræ and pronotum; the mesonotum rather deeply rugoso-reticulate, with a not sparse covering of yellowish white hairs, the sides of the pronotum and the metapleuræ more densely covered with longer hairs; parapsidal grooves deep, not especially convergent at the scutellum, and continuous to the pronotum; a pair of smooth, rather widely separated anterior parallel lines, slightly divergent anteriorly, extending half the way to the scutellum;