CURRENT NOTES. 307 



logie" is an important paper by Mr. Merrifield, in which, from ex])eri- 

 ments reported, he is able to define, with some closeness, what ai'e the 

 effective temperatures, and at what stage they operate, that govern the 

 seasonal dimorphism of Arumlinia Icrana and Sclenia bilnnaria, and in 

 all probability of the lepidoptera of the holarctic region. He suggests 

 that in the tropical and subtropical faunas moisture may have a greater 

 influence than temperature. Arctic dimorphism consists in the ap- 

 pearance of "winter" and "summer" phases according to the 

 incidences of temperature. These " phases " have a long and a short 

 pupal period as their essential character, a difference in " mass " is 

 also usual, other characters as facies, niarkings, colouring, etc., are 

 also associated, but are less essential, as they can be affected by 

 temperature conditions that are powerless to change the one phase 

 into the other. When hatched the larvfe can assume either "phase" 

 according to temperature conditions. A "spring" temperature applied 

 during the earlier larval stages produces the " summer " phase with 

 short pupal period. A "summer" temperature, similarly applied, 

 leads to the "winter" phase. A " spring " temperature is about 

 5-i°F., " summer " 60°F. to 65°F. But a remarkable point is that 

 these temperatures are means of a low night and a higher day 

 temperature, which are, when so alternating, more effective than a 

 constant temperature. The paper is worth careful study, without which 

 the brevity of our summary may be in some points misleading. — T.A.C. 



The ( 'cDiadiau Eutomnloi/ist for August has an interesting note by 

 Dr. J. McDunnough on the haliits of llepiahis hypeiboreits, Mosch. 

 He was collecting on Mount Hood, Oregon, when he noticed a small 

 moth darting with extreme rapidity in an erratic zigzag flight up and 

 down a slope, always keeping in the hottest sunshine. He managed to 

 secure some specimens, and to his surprise found them to be Hepialids, 

 the habit of flight being very different from that of the other N. American 

 species of the genus which, ordinarily, are dusk fliers. Later on he 

 discovered a virgin $ ascending a grass-stalk, and on arrival near the 

 top, " it folded the hindwings closely around the body and commenced 

 vibrating the forewings rapidly ; almost immediately the summons 

 was answered, a S appeared on the scene, and before I could prevent 

 it, coition had taken place" (the doctor's own words). The pairing- 

 habits here recorded are very interesting, and I believe hitherto 

 unrecorded. The flight in hot sunshine, however, is parallelled by 

 lle))ialus j)i/renaiciis var. alticolor of the Pyrenees, where this summer 

 we took it at about 7,500 ft. on the pass over into Spain, known either 

 as the Porte de Gavarnie or the Port d' Espagne, according to which 

 side you happen to be on. — G. T. B-B. 



In the June number of the Annales de la Soriete Eutoiiiulot/icjiie de 

 Behje, M. C. Emery, of Bologna, describes and illustrates a simple 

 apparatus for measuring exactly, and without much trouble, the parts 

 of small insects. It consists of a metal base serving either as a stand 

 or a handle, one end of which carries a transverse scale marked in 

 fifths of a millimetre, above which is fixed a lens of about 3 in. focal 

 length, whose focus falls on the graduation. The insect to be measured, 

 held either by the hand or fixed on a stand, can then be inserted 

 between the lens and the scale and the measurement ascertained. The 

 writer does not claim for this arrangement that it can measure with 

 any approximation to correctness objects less than one-tenth of a 

 millimetre. He emphasises the necessity for actual measurements by 



