15 
1891.] W. Doherty — A List of the Butterflies of Engano. 
protected of the Danwidm, and yet they are not brightly coloured, they 
have no alar scent-glands, and the anal tufts are the smallest in the 
whole family, and give the least fragrance. 
Apart from those producing the odour pervading the whole body, 
four different classes of scent-glands have been pointed out. 
The first are the impressed silky streaks of altered scales on the 
forewings of some Euplceas, often called brands. Mr. Distant oddly 
enough calls these pseudo-scent-glands, taking the falsity of their claims 
for granted, while assuming to leave the question open. The marks in 
question seem to consist of scales only, and 1 have not yet observed any 
glands connected with them. Though not very conspicuous in some 
cases, they may be addressed to the eye of the female, and help her to 
recognize the male of her species. For odours vary but little in the 
Ewploeas, and the amount of mimicry is so great that in most localities 
there are several species similarly coloured but bearing different sex 
marks. In any case these brands can hardly be protective, and the 
assumption by some writers that a species furnished with them is better 
protected, and more likely to be a mimicked than a mimicking form, is 
without foundation. 
The variously-coloured velvety patches on the hindwing of Trepsi- 
chrois, Salpinx etc., are no doubt true scent-organs. In the case of 
Trepsichrois midamus the odour is sometimes quite perceptible in the 
detached hiudwing, while in Salpinx and Calliplcea it is apparently 
excited by friction against the forewing. In some cases, such as Euplcea 
oceanis, described below, the velvety area is on the underside of the 
fore wing. 
The “ pouches ” on the hind-wings of certain species of Danais, 
such as T). Umniace, are probably true scent-organs, though neither Pro- 
fessor Wood-Mason, who has given them special attention, nor my- 
self, have been able to detect any odour. He has kindly shown me 
a microscopic section of the pouch. The cavity is lined with a semi- 
circle of long cylindrical cells radiating from it, their nuclei near their 
inner ends, the outer wall of the mass thick and chitinous, the inner 
membranous, with the attached scales aborted. According to Professor 
Wood-Mason, the odour-giving fluid is presumably manufactured iu 
these cells, and not merely drawn from the body and stored in them. 
An account of these pouches, apparently made from the study of dried 
specimens, has appeared in the work on the “ Duf tapparate indo-austra- 
lischer Schmetterlinge,” by Dr. Erich Haase of Dresden. 
Finally there are the abdominal tufts which we find in this family 
alone of all butterflies. They resemble those of the Callidulidoe, but 
are more specialized, though proportionately smaller than in these and 
