ON THE WING-SCALES AND THEIR tlGJlENT IN LEPlDOtTEKA. 70 



My observations teach me that no air enters the permanently white 

 scales, or any others, until the pigment is fully elaborated, and 

 that air enters all the scales, pigmented as well as white, for the first 

 time, and finally, as the last stage in the development of the scales, not 

 very long before, and possibly often not till after, the emergence of the 

 imago from the pupa. I examined the wings in the fresh state, 

 without staining or preparation, so that, whilst missing much of the 

 histology that Mr. Mayer demonstrates, I probably had a more correct 

 view in this particular matter of the air ; at no early stage whatever 

 was there such a change in the specific gravity of the wing as the 

 presence of air in the scales would cause, a change that, many of my 

 manipulations being carried out under water, would have made very 

 unmistakably apparent. 



In the second place, in the " white stage," there was never any of 

 that opaque chalky whiteness that is characteristic of the air-filled 

 white scales of F. atalanta. Thirdly, the white scales of P. atalanta 

 (and others) were clearly full of fluid up to the date of the complete 

 pigmentation of the other scales, and were diflicult to see, instead of 

 white, as afterwards. 



The clear fluid which fills the scales at the white stage is probably 

 not the " hjemolymph," and it seems very doubtful whether the haemo- 

 lymph simply, ever enters them, but rather a secretion from it, con- 

 taining the matters necessary for going through the chemical change, 

 resulting in pigmentation. In the white scales it never contains this 

 pigment basis. 



The white scales in the fringes of P. atalanta form very easily 

 observed subjects for this investigation ; the frequency with which 

 they passed under my observation as objects somewhat difficult to make 

 out, owing to their clearness and transparency, at various and even 

 very late stages of the pigment development in the coloured cells, the 

 specimens being perfectly fresh, and no traces of air (either as 

 completely filling the scales, or as separate bubbles left behind 

 in them) existing, seems alone sufficient to justify my doubt as to the 

 accuracy of Mr. Mayer's conclusions on this one point. 



Something might, perhaps, also be said as to the antecedent 

 improbability of a temporary occupation of the cells by air in the way 

 described. 



Contributions to the fauna of the Dauphine Alps. 



IV. — The Butterflies of Boukg d'Oisans. — Sexual dimorphism of 



POLYOMMATUS. DrINKING BUTTERFLIES. PaRARGE MEG^ERA AND 



P. MiERA ON THE SAME GROUND. On THE OCELLATION OF ErEBIA 



NEORIDAS. 



By J. W. TUTT, F.E.S. 



From August 12th until the 19th, we collected in the neighbourhood 

 of Bourg d'Oisans, a small village situated on the left bank of the 

 Romanche, at an elevation of 2,400 ft. above the level of the sea. The 

 river here has spread out a great plain, bounded on either side with 

 lofty mountains, the precipices often rising almost sheer from the 

 plain to a height of from 1,000 to 1,500 ft., and presenting, on their 

 exposed faces, remarkable instances of contorted stratification. The 

 country worked here was the fields and slopes directly behind the 



