TTybrids of S])hingiclae. Bj^ Dr. P. Denso. 261 



a drop of honey and water into them. — If many species are kept in the cages, it is necessary to watch person- 

 ally whether pairing takes place and to protect by some mean.s or other a pair found in copula against being 

 disturbed by the other specimens. Next day the hybridised + is best sleeved on to the live food-plant of the 

 caterpillar of its own species. The bag should not be too large, as otherwise it would be unnecessarily difficult 

 to collect the eggs, which it is advisable to do, as in many cases the young larvae feed on the food-plant of 

 the paternal species. When the larvae have emerged from the eggs, they should be put on to a growing plant 

 and the conditions of life be rendered, if possible, more favourable than in the wild state. The greatest pos- 

 sible care should be taken of the specimens, so as to detect at once the appearance of infectious diseases of the 

 organs of digestion and to take early means of preventing the disease, so frequent among hybrid caterpillars, 

 from spreading. Very often the hybrid larvae suffer from a feeble constitution. This is especially laoticeable 

 in the full-fed caterpillars, which are often unable to pupate and frequently do not even make preparations 

 for the pupal stage. There are of course no means of altering that, the breeder of hybrids must be prepared 

 that he will possibly not get a single chrysalis from hundreds of large and apparently strong larvae. This 

 weakness of the constitution is accentuated in the larvae of secundary hybrids. It is advantageous to accelerate 

 the feeding up as much as possible, by raising the temperature if necessary, and by a constant supply of fresh 

 and healthy food. The treatment of the pupae does not require any special remarks. In the case of Celerio 

 and Pergesa hybrids the moths have a tendency of emerging early, and if they go tlirough the winter they are 

 to be treated like the chrysalisses of the parent species. 



Some remarks about the pairing may be added. Although it sometimes appears as if warm sultry nights 

 are particularly favourable for hybridisation, cross-pairing also occurs in cold starry nights. The ol)servations, 

 however, are still insufficient for drawing conclusions as to the influence of the meteorological conditions. It 

 easily suggested itself to do away with the external conditions as well as the perhaps purely individual internal 

 stimulants which cause the moth to copidate, and to try artificial impregnation. However, no success has 

 been attained. Artificial parthenogenesis did not occur, and artificial fertilisation with sperm of the same 

 or other species had no result whatever. 



Premary and secondary hybrids as well as crosses between races are so far known of the genera, Mimas, 

 Smerinthus, Calasymbolus and Amorpha on the one hand and Celerio and Pergesa on the other. It is easy to 

 understand that hybrids occur rarely in a natural state, by far the greater number of the hybiids known being 

 obtained in captivity. It is often very difficult in the case of wild hybrids to establish the parent species with 

 certainty, the necessary corroboration being often only obtainable by exjieriment with captive specimens. On 

 the whole the hybrid exhibits a diffuse mixture of the characteristics of the parents, inclining rather more 

 towards the phylogenetically older parent species. However, some cases are known in which the characteristics 

 of the parents were not fused, but appeared side by side lite the stones in a mosaic. Frequently the paternal 

 side predominates, but striking anomalies have being observed in this respect, especially among secondary 

 hybrids. As regards the caterpillars, they also exhibit a fusion of paternal and maternal characteristics, but 

 the most noteworthy phenomenon observed at them is ,, anticipation", that is to say, that the larvae of hybrids 

 reach certain stages in their ontogeny earlier than the larvae of the parent species. 



The old rule that the larvae feed on the food-plant of the maternal species has been proved incorrect 

 by a great number of observations, which again renders it difficult to establish the parent species of a hybrid 

 found as larva at large. Another opinion formerly likewise held generally that the wild hybrids are sterile also 

 requires modification. Fertility is indeed very often strongly reduced, particularly in the ?¥, but nowadays 

 quite a nuniber of secondary and tertiary hj'brids are Icnown, which prove that fertility does obtain. However, 

 the generative organs atrophy more and more in the successive generations, even in the case of crosses between races. 



1. Hybrids of tlie (Jeiieni 31iiujis, Smeriiitlius, Caljisyniholiis aiul Aiiiorplia. 



A. Primary Hybrids. 



M. hybr. leoniae Standj. (Mimas liliae tiliae L. J x Smerinthus ocellafa ocellata L. f) (43 e). This hybrid Ironiae. 

 hastlie elegant shape of tiliae, which it resembles closely in fades. It also bears like tiliae on the forewing a conical 

 spot beginning broadly in the middle of the costal margin, gradually narrowing, slightly curving towards the 

 distal margin and gradually disappearing towards the hind margin. Between the conical spot and the distal 

 margin there is a diffuse undulate line extending from the costal to the hind margin nearly parallel to the distal 

 margin. From ocellnta the hybrid has particularly the dark thoracical stripe and the black rounded anal patch 

 of the hindwiiig, this patch bearing often a bluish grey arc at its upper edge. Between this anal spot and the 



