0 
INTRODUCTION. By Dr. A. Seitz. 
their swarming period, although from their slender body provided with relatively large wings we might infer 
their ability for an easy and continual flight, as for instance in the Morplio, Urania, Hestia etc. 
Nowhere h] the world is the average size of the Geometridae as low as in Africa. The palaearctic, Indian, 
American, and even Australian Hemitheinae and Geo-metrinae mostly excel the African members of the same group 
to a considerable extent, so that many Africans look like undersized insects compared with their relatives from 
other countries, for instance the Mvmandria or Xerwchroma from Cape Colony or even Madagascar compared with 
the Indian or Papuan Pingasa, Terpna and Aelochroma, the African Gelasrna with the Papuan Chrysochloroma, 
the eastern palaearctic Gel. grandificaria, illiturata with the African mostly insignificant Prasinocyma, and the 
latter besides with the Papuan Pr. bicolor, or dioscorodes or their Indian relatives. Also in single cases the size 
of Indian Geometrinae, such as Medasma, Xandrames or Elphos is hardly or never attained by African Boar- 
nninae, to say nothing at all of the large Urapterygmae. 
A considerable number of the African Geometridae prefer the sunshine, in the same way as numerous 
European and particularly South-American Geometridae fly in the daytime. The Aletis and Cartaletis do this 
as a matter of course, because the daylight is required for the effect of mimicry among moving animals. 
It was only in the last decades that this relationship of the Ethiopian Geometridae to mimicry was more 
clearly elucidated. The fact that a great many species exhibited a striking resemblance which could not be 
explained otherwise than by mimicry, had of course struck already the first collectors who ventured to penetrate 
into the more inaccessible parts of the African continent. And it would be rather absurd to deny the striking 
assimilation for instance between Aletis dissoluta Gaede (1 e) and Xanthospnlopteryx poggei (Vol. XV, pi. 1 b) 
which fly together on L. Tanganyika. Here in Africa we meet with the same fact as in South America and 
India, that harmoniously coloured lepidoptera unite in oecologically separated communities, for instance between 
Aletis helcita (1 e) and Phaegorista similis (Vol. XIV, pi. 17 b), the above mentioned Xanthospilopteryx and 
eYeiiDiuina, {E'uphaedra ruspma, eleus, Vol. XIII, pi. 42 b). Whilst this group externally approximates to the 
facies of the most common African lepidopteron, Danais chrysippus, the Cartaletis (e. g. 0 . variahilis [1 g]) seem 
to approach certain Acrnea (from the encedon or sganzmi-gronii), which again provides numerous lepidopterous 
species not being allied to each other with the same uniform, as for instance certain Mimacraea, Secusio and 
others. The relationships between the models and the copies are still obscure; but the discovery of the larva 
of Aletis by Lamborn has iiroved the latter to be very variegated and striped zebra-like, so that one might 
think of an internal protection; this assumption is also supported by the yellow juice emanating from the 
Cartaletis when squeezed. As the Aletis are systematically connected with the Cartaletis by transitions 
(Aletis erici), probably also their internal properties are not very divergent. We should therefore not wonder 
to see models in the Geonietrids, if the protection of their doubles, the Acraea, had not been proved by way 
of experiments (especially by Marshall). Here in the Ethiopian region we find the parallel case to analogous 
phenomena in South America, where we see Arctiidae, Ithomiinae and Pieridae, which are mostly protected 
themselves, adapted to each other. 
As in other oldi 7 e/erocera-families, the degree of adajitation to the suiToundings is likewise very complete 
in the Geometridae. The larva of the Abyssinian Coenina dentataria- living on Nile-acacias shows on the dorsum 
fleshy, pointed, bent appendages which exactly represent the thorns of the food-plant. The larvae of Khodometra, 
which is the most common and most widely — even in the deserts — distributed African Geometrid genus, resemble 
the stalks of leaves or blades in exactly the same way as most of the European smaller Geometrid larvae. The 
imagines exhibit the colours of yellowish-red stones and of grey, clayey jiarts of the soil, the more since trunks of 
trees, which might be used as resting-jilaces, do not occur in those districts, as we mentioned above; on the other 
hand, straw-coloured, unmarked surfaces of the wings help to conceal the imagines resting on blades, especially 
if they keep their wings accordingly placed, as for instance the above mentioned Rhodometra, which sling their 
wings completely round the blade. In a similar way the straw-coloured E-uchlaena take up such a position 
that they cling to small leaves which have turned yellow, and the great part of the common Geometridae of South 
Africa are adapted according to the type of our Gonodontis, Colotois, Selenia or Crocallis, representing dry and 
shrivelled leaves, as for instance the Eupagia, Drepanogynis, Derrioides etc. 
On the whole, the Geometridae predominate nowhere in the Ethiopian region so much over the other 
Heterocera families as it is the case in the palaearctic (especially the eastern palaearctic) I’egion. With very 
few excejitions, most of the African districts are almost entirely devoid of day-flying Geometridae-, excepting the 
Aletis and Cartaletis, only the Nathemsa Wkr. are Geometridae spontaneously swarming in the daytime like the 
qtalaearctic Aspilates', all the others presumably fly in the daytime only when they are started up. But they 
have a light sleep and are therefore easily driven out of the brushwood. 
Moreover, we cannot expect to find many iieculiarities in such an old and equably distributed family 
as the Geometridae are, in their various patriae. In Africa there does not exist any connection with other lepi- 
dopteral families, since the first subfamily — the Brephinae — being still rather Noctuid-like is absent there. 
However, the few species of the OenocJiromine genus Petovia (1 a) are to some extent allied to the Brephinae 
and may be a kind of junction to the Noctuids. 
