In the Alps generally there is no definitely intermediate population; nor I believe, is any such population met with in the north where the arctic _bryoniae_ meets _napi_, but as to this I have no precise information. One curious fact, however, must be mentioned, namely that there is a population that can probably be so described with fairness established at Mödling near Vienna. This is not in any sense an Alpine locality, and does not, as I am told, differ in any obvious way from the other suburbs of Vienna. Dr. H. Przibram was so good as to send me a set taken at this place, representing a second brood, and they were decidedly heterogeneous, ranging from an intermediate form such as _bryoniae_ fertilised by _napi_ usually produces, to a light yellowish second-brood type with little dark pigment. There are also two actual _bryoniae_. Whether true _napi_ also occur there I do not know, but I have no doubt they do. It would be well worth while to investigate the Mödling population statistically, and to breed from the intermediates which might not impossibly prove to be heterozygotes. There are also records of such intermediates being occasionally found in some parts of Ireland, in the north of Scotland, and in south Wales,[19] but I do not know of any regular colony of these forms. We can scarcely avoid the inference that one or more of the factors which make up _bryoniae_ may be carried by these intermediates. It is not clear why their interbreeding does not produce actual _bryoniae_ occasionally. If this occurred, the probability is that the fact would be known to collectors, at least in the British localities. The absence of true _bryoniae_ must, I think, be taken to mean that some essential factor is absent from these intermediates. To sum up the evidence, the facts that are clear may be thus enumerated: 1. _Napi_ and _bryoniae_, or in the Italian Alps, _napaeae_ and _bryoniae_ frequently meet each other. 2. They cross without difficulty, producing fertile offspring. 3. But in the levels at which they overlap there is no intermediate population, and only occasional intermediate individuals. 4. In certain parts of the distribution of _napi_ similar intermediates sometimes occur, and at one place (Mödling) they are so frequent as apparently to constitute a colony. 5. As to the genetic relations of the two forms there is no complete certainty. Indications of segregation have been observed in some cases, but there are several factors concerned and they are liable to some disintegration.