MALACOSOMA. 



J5 



with a yellow line scarcely 1mm. in width ; on the brown hindwings there is some- 

 times a paler median line indicated ; on the underside of both wings, however, a 

 light central band is always traceable. The wings are not so transparent as in 

 franconica, but more so than in neustria, especially the forewings. The thorax and 

 body are brownish-yellow, the former always of a lighter tone of colour than the 

 latter. On the hindwings, on nervures 3 and 4, the fringes, which are yellow in 

 franconica, are brown as in neustria. One is reminded most of franconica by the 

 contrast of the colour of the wings on the one hand and the thorax and abdomen 

 on the other, and the perceptibly transparent wings. The points that most remind 

 one of neustria are the distinct yellow border of the central band of the forewings 

 and the dark fringes on nervures 3 and 4 of hindwings (Standfuss). 



(2) Malacosoma neustria $ x castrensis 5 . — At the same time as 

 the former experiments in crossing neustria and franconica were being 



' carried out, M. castrensis var. veneta was emerging, and neustria $ s 

 were paired with ? s of the latter. The same three points as to egg- 

 laying noted under neustria x franconica were observed, viz., some of 

 the ? s were unable to discharge their eggs and died, others laid their 

 full quantity of eggs at once, whilst others did so after a second pairing. 

 Of these, four batches were obtained, and the larva? developed much 

 more favourably. Each of the four batches numbered from 400-600 

 eggs, the numbers of larvae emerging being respectively 120, 143, 161, 

 204. The larvae at first seemed to feed well, but gradually after the 

 first, second, and especially the third, moults, died off, so that finally 

 only a dozen hybrids emerged, curiously enough all females — or, to 

 speak more correctly, a form with the external appearance of ? s. 

 Some of these hybrids were crippled, and the body of one on being 

 opened was found to contain the rudiments of an ovipositor and an 

 extraordinarily developed mass of fat (a quite unusual occurrence in 

 Lachneid females). This form is noted as follows : — ■ 



/3. hybr. schaufussi, Stdfss., " Handbuch, &c," p. 63, pi. iii., fig. 4 (1896).— The 

 markings of the hybrid neustria x castrensis are intermediate between those of the 

 two species, the inner transverse line making a small pointed angle into the median 

 band (more rarely a small curve) just before reaching the costal margin. This is 

 the only point, perhaps, worth noticing, for the females of neustria and castrensis 

 scarcely differ at all in wing form, and the only constant difference appears to be in 

 the boundary lines of the median band ; in castrensis the inner line makes a con- 

 siderable bend into the band before the costa, in neustria this is absent (Standfuss). 



(3) Malacosoma franconica £ x castrensis $ and the reciprocal 

 cross 31. castrensis $ x franconica J . — These reciprocal crosses were 

 obtained by both Standfuss and Penzig. In neither of these crosses 

 did the ? s die without egg-laying as a result of the pairing, although 

 unfortunately after living some time several of the ? s laid no eggs. 

 Two necklets of eggs were obtained of castrensis x franconica, from 

 which 70 and 92 larvae were obtained, but they all died without eating 

 anything except the eggshells. Of franconica x castrensis a batch of 

 400 eggs produced 120 larvae, of which only three reached maturity, 

 and of these only one pupated, which yielded a crippled ? . This is 

 described as follows : — 



y. hybr. penzigi, n. hybr. — The central band always wanting in franconica was 

 here weakly indicated, but of the form of wing the crippling prevents anything to be 

 said. The ovipositor also was in this extremely ill-developed and the fat-body 

 prominent (Standfuss). 



Selmons records (Sue. Ent., January, 1894) that he obtained a 

 pairing between 31. alpicola $ and 31. castrensis ? . Only three eggs 

 were laid and these infertile. He also obtained seven pairings between 

 3 31. castrensis and ? 31. alpicola, and four of the females deposited 

 a large number of eggs, all of which proved infertile. 



