LACHNEIDES. 435 



species have been included by various authors within its boundaries. 

 The imagines are usually large and densely scaled, they have no 

 frenulum, and the costal area of the hindwing is sometimes remarkably 

 developed. The male antennae are highly specialised, and have long 

 pectinations ; there is considerable sexual diversity exhibited, and the 

 difference in the habits of the sexes is also most marked. 



We are indebted to Aurivillius for an excellent revision of the 

 Palrearctic species (Iris, vol. vii., pp. 121-192). This author defines 

 the group as follows : 



Antennae maris pectinatae, feminae pectinatae. serratse ant fere simplices. Alas 

 retinaculo nullo. Costa quinta alarum omnium ex angulo postico, sexta ex angulo 

 antico cellulte orientes. Costa dorsalis alarum antiearum unica, basi non furcata. 

 Costae dorsales alarum posticarum duas, prima in angulum analem, secunda in 

 marginem egrediens. Costa septima alarum antiearum aut e costa sexta vel oetava 

 aut libera e cellula oriens, costae nona et decima semper ad basin conjunctae. Cellula 

 discoidalis alarum omnium parva et angusta, medium alae haud attingens. Tibiae 

 posticas bicalcaratas aut inermes. Lingua nulla aut brevissima. Larva : Pedibus 

 thoracibus 6 et abdominalibus 10 semiannulatis (in segmentis 0-9 et 13 sitis) 

 praedita. Caput et corpus plus minus dense pilosa, squamosa vel rarius 

 aculeata. Verrucae saepissime nullae aut obsoletae, rarius magnas et distinctae ; 

 verrucae dorsales, si omnes (4) adsunt, etiam in segmentis 2° et 3° in duabus seriebus 

 collocatae sunt. Pili non solum in verrueis, sed undique in cute inserti. Pupa : 

 Cute tenui instructa, in folliculo plus minus denso, sericeo semper inclusa. 



The Lachneid egg is of the flat type, the micropylar axis horizontal 

 and usually considerably longer than either of the other axes, of which the 

 vertical is the shorter. It may be either oval (occasionally approaching 

 circular) or roughly quadrangular in outline, slightly depressed on the 

 upper surface, and with the micropyle placed conspicuously at one end 

 of the horizontal axis. It is generally shiny, sometimes somewhat 

 opalescent, apparently smooth, but under a sufficiently high magnify- 

 ing power is usually seen to be covered with an exceedingly fine poly- 

 gonal reticulation, a minute dark knob being situated at each of the 

 angular points. 



The mode of egg-laying of the Lachneids is very diverse, and our 

 few British species exhibit a striking dissimilarity in this respect. 

 Perhaps the most remarkable methods adopted are those seen in 

 Malacosoma (neastria, &c), and Lachneis (lanestris). These species lay 

 their eggs round and round a twig in the form of a necklace, those of 

 the first in rings, of the latter in spiral form ; the eggs of the Mala- 

 cosomas also are embedded in a stiff liquid glue, whilst those of Lachneis 

 are covered with a thick clothing of long silky hairs, mouse-coloured 

 in tint to the naked eye, but seen to be formed of black and white 

 fibres under a microscope. At first sight it would appear that the eggs 

 of these species are upright and not flat eggs, i.e., their micropylar axis 

 appears to be vertical and not horizontal to the surface on which they 

 are laid, but further examination shows that this is not so, that they 

 are in reality laid one upon the other and not upon the twig round 

 which they are placed, being but loosely attached thereto in the Mala- 

 cosomas, and readily slipping off in mass if the twig contract by drying. 

 Their resemblance in position to upright eggs is only then an extreme 

 development of the condition observable in Endromis aud the Saturnias 

 in which the eggs are piled upon each other. The eggs of Trichiura 

 crataeiji and Poecilocampa populi are both laid in linear series side by 

 side on a branch, their long axes parallel, in numbers extending from 

 four or five to a dozen, those of the latter species being often, however, 



bb2 



