36 BRITISH LEPIDOPTERA. 



6. L. hybr. inversa [= (meridionalis x viburni, whitehaired, 2nd gen.^ x 

 sicula\ — 2 $ s and 4 ? s. The males peculiar, one being very near the $ parent, with 

 well-developed narrow bands, the other with the transverse band on the forewing restrict- 

 ed and not quite reaching the costa ; that on the hindwing absent, the marginal area (in- 

 cluding normal position of band) being very dark buff and almost unicolorous, the 

 fringes paler ; the ? s incline rather to meridionalis x viburni than sicula (Bacot coll.). 



7. L. hybr. complicate/. [= <? f sicula x meridionalis) X ? [(meridionalis 

 X viburni) x (meridionalis x viburni)]].— 2 <? s of most bizarre appearance ; 

 a peculiar mixing of the dark chocolate and russet tints of the males of merid- 

 ionalis and sicula respectively, the transverse band on the forewing being 

 reduced to a narrow line, that on the hindwing still narrower and tending to 

 obsolescence (Warburg coll.). 



In these crossings there appears to be a distinct tendency for the 

 progeny to follow the male parent. This, however, is much modified 

 by the particular race from which the parents come, a $ quercus influ- 

 encing the progeny more than a $ meridionalis or $ viburni, and these 

 more than a $ sicula. One suspects that the callunae and quercus 

 forms are the oldest and most generalised, and sicula the newest and 

 most specialised, and that the tendency in crossing is for the progeny 

 to revert to the oldest form. Bacot, on larval characters, considers that 

 the British quercus is the most ancestral form, and finds in the hybrid 

 larvae more marked tendencies in the direction of quercus and callunae 

 when one or other of these is one of the parent forms. 



Giard touches on the question of pcecilogony in Lasiocampa 

 quercus, L. var. viburni, L. var. callunae {Ann. Soc. Ent. France, lxiii., 

 pp. 128 — 135). The two last-named he notes as the southern and the 

 northern representatives of L. quercus. He writes : " Although it is 

 almost impossible to separate the adults of these three forms, Guenee 

 has discovered that the young caterpillar of L. var. callunae differs 

 from that of L. quercus, but that the divergence diminishes after the 

 first moult and finally disappears.* One may attempt to see in this 

 dissimilarity of the larvae in the early state a proof of the primitive 

 separation of the two species; but the habitat differs sufficiently to 

 explain this divergence. One of the two forms, without doubt L. var. 

 callunae, represents the first ancestral larva,** which is modified in L. 

 quercus and L. var. viburni, and this species may truly be considered 

 as a pcecilogonic f form slightly modified in the adult stages." 



The larval hairs have already been referred to (a //tea, vol. i., p. 100) 

 as showing considerable urticating properties, the finely-pointed urticat- 

 ing hairs getting under the skin and setting up considerable mechanical 

 irritation which frequently lasts for several days {vide also South, Ent., 

 xviii., p. 5 ; Long, loc. cit., xix., p. 45, Connon, Ent. Rcc, iii., p. 20, &c). 

 The colour of this urticating fur is largely characteristic of the various 

 races of the species, and, in inbreeding and crossing the different forms, 

 Bacot has noted many important results bearing on the broader 

 questions of heredity. He describes the larvae of the various races on 

 which he experimented as exhibiting the following characteristics in 

 their adult forms : 



* Not by any means docs the difference always entirely disappear, sec Bacot's 

 notes almost directly following. 



** Recent work suggests querents larva as the oldest form, larvae of viburni and 

 callunae both being" more specialised although in different directions. 



t Insects that have dissimilar larvae, at different points of their geographical 

 distribution, at different seasons of tin- year, or under different conditions of nutrition, 

 whilst the adults arc very similar to each other, and present very slight modifica- 

 tions, arc said to be pcecilogonic (i.e., exhibit the phenomenon of pcecilogony). 



