ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
623 
systems of these various authors confirm one another. As Mr. Tutt 
states that lepidopterists have had no system of classification except a 
hotch-potch, it is clear that the thanks of systematic zoologists are due 
to the authors who have attempted a scientific classification. 
Affinities of the Lepidopterous Wing.* — Mr. Y. L. Kellogg discusses 
the relations of the wings of butterflies to those of the Trichoptera. He 
finds that the lines of specialization exhibited by the wings of the latter 
are strikingly parallel in general character with those exhibited by the 
Lepidoptera. A more primitive sub-equality of the wings, shown among 
the Lepidoptera only by the Jugafle, is retained, but there is an obvious 
tendency towards a narrowing of the wings. It seems to be probable 
that the frenate type of wing had its origin in an earlier type which was 
essentially jugate, but which possessed frenulum-like structures of a 
character to be easily developed into the existing highly specialised 
frenate condition of the Noctukke and others. 
Seasonal Dimorphism of Ithopalocera.t — Mr. C. W. Barker has 
some notes on the seasonal dimorphism of Rhopalocera in Natal. The 
seasonal variations of double or many-brooded species are found to be 
of a very marked character, and to modify the facies so considerably as 
to lead to much confusion in the determination of species and varieties. 
This form of variation is most marked in the Pierinse. Two rules which 
generally hold good as characteristic of the changes and modifications 
which occur, and which serve to distinguish the dry-season form from 
its summer or wet-season form representatives, may be thus formulated : 
(1) Smaller size and a disposition to greater acuteness in the apices of 
the fore wings ; (2) The dark markings on the upper side of the wings 
become contracted or even obsolete. The markings on the under side 
become suffused or merged in a generally duller and darker ground- 
colour. Practical field observations during a course of years have con- 
vinced Mr. Barker that many of the so-called species are simply seasonal 
varieties of one and the same butterfly; but he is unable to determine 
whether the modification of the facies of dry-season forms is due to 
protective mimicry, or whether it is the mere sympathy of organisms 
with their surroundings. Details are given as to a number of species, 
and it is urged in conclusion that the identification of species can best 
be aided by paying the utmost attention to dates of capture, with due 
regard to the character and climate of the country the butterfly may have 
come from. The present system of adding species to species on the mere 
ground of some slight modifications of the markings of the upper or 
under side, and sometimes on the strength of one or two examples, is 
most misleading. 
Secretion of Potassium Hydroxide.! — Mr. 0. H. Latter has some 
further notes on the secretion of potassium hydroxide by Dicranura 
vinula, and similar phenomena in other Lepidoptera. He finds that the 
imagines of eight species secrete from the mouth an alkaline fluid on 
emerging from the pupa. The three species of Dicranura wear what is 
called a shield, derived from the pupa-case as they emerge, and they 
* Amer. Natural., xxix, (1895) pp. 709-19 (10 figs.). 
f Trans. Entomol. Soc. Lond., 1895, pp. 413-28. J Tom. cit., pp. 399-412. 
