Art. XX.—Note on a peculiar Neuration in the Wings of some Individuals of Percnodaimon pluto, a New Zealand Butterfly.
[Read before the Philosophical Institute of Canterbury, 30th November, 1882.]
When examining some specimens of P. pluto I noticed that the costal nervure of the primary wings of one of them was bent inwards and united to the first subcostal nervule, the united nervure and nervule running thence in one vein to the anterior margin, as shown in the annexed diagram, fig. 1a. In ordinary specimens the first subcostal nervule is not present, and the costal nervure is of the ordinary form as shown in the annexed diagram, fig. 2. (The diagram is twice the natural size of the wing).
The discovery of this peculiarity led me to examine very carefully all the specimens of P. pluto in my collection, and those in the collection of Mr. J. D. Enys. These collections consist of 33 specimens taken on a mountain near Mr. Enys' station, Castle Hill, Porter's Pass, 21 on Mount Hutt, and 1 on a mountain near Lake Guyon (Nelson Provincial District). Six males and one female of the Castle Hill specimens, four males of the Mount Hutt, and the one male of Lake Guyon, have the united veins, and are smaller, but in other respects do not appear to differ from the ordinary form. In all the specimens having the united veins, such veins are alike in form, position, strength, and point of junction, and all the other veins are uniform with those of the ordinary specimens. No other irregularity of neuration appears in any of the specimens, nor does there appear to be any other tendency to variation in the species.
Does the neuration of the wings of Lepidoptera furnish a reliable character for determining families and genera? I will not attempt to answer this question, but I submit the above facts for the consideration of entomologists.