104 THE entomologist's record. 



the last few weeks, in newly emerged specimens of Ardia lubricipeda, 

 A. menthastri, Smerinthus oceliatus, Limacodes iestudo, etc. During 

 expansion, pricking the membrane at any portion of the wing results in 

 the exudation of a drop of fluid. This f^uid disappears rapidly when 

 expansion is completed, and dries from the base. When saccular dis- 

 tension takes place, the mtre fact of killing the insect and leaving it to 

 dry does away with the distension, the fluid evaporating, but in this 

 case the membranes, previously stretched by the excess fluid, contract 

 and dry irregularly. If the exudation of the insect had any connection 

 with the fluid by which expansion is brought about, it would be difficult 

 to explain why newly emerged insects, if touched or pressed will exude 

 first, and the wings afterwards expand quite normally. — J. W. Tutt. 

 July, 1 89 1. 



Generic Nomenclature and the Acronyctid^. — With reference 

 to Mr. Tutt's remarks in the June part of the Entomologists Record, I 

 may say that the whole question of entomological nomenclature is 

 extremely difficult and complicated, and cases continually arise which 

 can hardly be decided by any existing rules. Some of these, but by 

 no means all, are considered in the preface to my Catalogue of Neuro- 

 ptera Odonata. The number of generic names of insects (some in 

 current use, others ignored, some characterised more or less completely, 

 and others not at all) is so vast that I think it most desirable to avoid 

 adding to the mass unnecessarily. Hence I would never rename a 

 genus for which any existmg name, characterised or otherwise, is 

 available. To quote from my preface (p. v.) : — "The limits of a genus 

 are always variable, and its characters subject to modification, both 

 according to the increase of our knowledge, and to the divergent views 

 of different entomologists ; hence, although no generic name ought to be 

 issued without a description, yet the fixing of a type, which must always 

 be an identifiable £[)ecies placed in it when the generic name is used for 

 the first time [and one which does not contradict the characters of the 

 genus, if any are given, or the meaning of the generic name, if it has 

 any] appears to be even more important, for no real certainty can be 

 obtained without. In fact the fixing of the type of a genus is to the 

 description what the figure of an insect is to the description of a 

 species." Hiibner was far in advance of his age, and perceived that a 

 much more minute subdivision of species was necessary than other 

 entomologists were willing to admit for fifty years afterwards, and he 

 tried various experiments in nomenclature with more or less success. 

 It was natural enough for Boisduval, in whose time 20 or 30 of Hiibner's 

 " Coitus" (as the latter called subdivisions corresponding to our modern 

 genera) were regarded as one homogeneous genus, to reject Hiibner's 

 work on principle ; but we cannot do so now, when we subdivide genera 

 to the same extent as Hiibner, only that we subdivide them differently, 

 according to what we consider, with our present increased knowledge, 

 to be more important characters. If every author who alters or improves 

 the characters of a genus considers himself at liberty to rename it, or to 

 impose a new name on any subdivision of a genus, without inquiring 

 whether any name exists which can lawfully be applied to it, we may as 

 well abandon the study of entomology as foredoomed to hopeless and 

 irretrievable confusion. 



I have not yet sifted the nomenclature of the Acronyctidce ; but I 



