298 BRITISH LEPIDOPTERA. 



oviducts containing no ripened eggs. Pairing also took place, though 

 with much less readiness than in either of the preceding cases, between 

 the hybrid males and some females of S. pyri. The number of fertile 

 eggs produced in the latter case was far smaller than in the cross with 

 S. pavonia. The secondary hybrids are described at length as follows : 



I. S. hybr. schaufussi, Stdfss. {bornemanni <? X pavonia $). — The larvae 

 at first closely resembled those of S. pavonia, but, in subsequent stages, the 

 influence of S. spini began to assert itself. They presented a very variable 

 appearance on reaching the fourth stage, which period, unfortunately, they did 

 not survive (toe. cit., pp. 86 — 87). [Fresh batches, however, have since been raised 

 to maturity by Dixey, from ova supplied by Standfuss in 1895, as we ^ as by 

 Standfuss himself (Ent., xxxiii, pp. 344 et seq., pi. hi., figs. 6-8).] 



This hybrid is important as one of the only ones that have pro- 

 duced fertile progeny of both sexes (Ent., xxxiii., p. 345). Standfuss 

 has inbred $ s and $ s of schaufussi, and succeeded in rearing two males 

 of the same brood of this crossing, i.e., schaufussi $ x schaufussi 2 , 

 the only pairing between true hybrid forms that he has yet obtained. 

 One of these is figured (Ent., xxxiii., pi. iv., fig. 3) and gives a very 

 curious impression. At first sight it appears to be an old and well- 

 known form, and the next moment an entire stranger. The creature 

 seems familiar when one simply regards the coloration which first 

 forces itself upon one's attention, as it agrees so entirely with a lightly 

 coloured S. pavonia 2 that it could easily be mistaken for such ; but 

 the creature gives quite a different idea when one notices that it is 

 without doubt a well-developed $ . In fact, this creature agrees 

 entirely in structure with that of a S. pavonia $ , but possesses the 

 exact coloration of S. pavonia % • By this crossing experiment the 

 bright phylogenetically younger male coloration is thrown back to 

 the phylogenetically older, less brightly coloured, $ type. The 

 second $ is similar to this $ in structure and size, but on the 

 upperside, on the outer border of the hindwings and in the centre 

 of the forewings, beneath the eye-spot, towards the hind border, 

 it possesses numerous rosy scales, and resembles the rare, somewhat- 

 red form of S. pavonia $ . 



2..S. hybr. standfussi, Wiskott (emiliae $ x pavonia ? ). — The larva? 

 of this hybrid are very variable. Their general appearance is that of a large *$". 

 pavonia. The cocoon and pupa are also near the same pareut species. The 

 perfect insect, like the larva, is variable ; it always, however, shows much resem- 

 blance to S. pavonia, and the sexes are dissimilar as in that species. The 

 margins of the wings are apt to be scalloped. The oviducts of the single female 

 that emerged contained mature eggs, but only about twenty, or one-tenth of the 

 normal number in S. pavonia or S. pyri. It is possible that these hybrids may be 

 fertile inter se (Handbuch, &c, pp. 87 — 91, pi. ii., rigs. 6-7). [See also Ent., xxxiii., 



P- 344-] 



3. S. hybr. rtsii, Stdlss. (emiliae d x pyri ?). — This pairing was only 



obtained with great difficulty, and, in four cases out of nine, the eggs, though laid 

 in normal numbers, did not hatch. In the remaining five broods only one per cent, 

 produced caterpillars. These at first closely resembled S. pyri, and in the second 

 stage still showed more likeness to J>. pyri than to the male pareut form. In the 

 third stage the S. pyri characters began to be lost, and in the fourth those of 

 S. pyri and S. pavonia were fairly balanced. After changing its last skin the 

 larva resembled a large S. pavonia, though its parentage was three parts S. pyri. 

 The perfect insects, of which only six were reared, were in many respects re- 

 markable. Unlike S. py>'i, they Mere sexually dimorphic, the females differing 

 little from those of S. emiliae, while the males showed a nearer approach to S. 

 pyri. The females were not dissected, but were probably sterile. Of the six 

 specimens, one was hermaphrodite, and three others showed a tendency in that 

 direction. These four were the produce of three separate females out of the five 

 that laid living ova. Standfuss draws attention to the fact that the normal occur- 



