BERGSTRASSER ON THE CLOUDED YELLOWS. 181 



water containing very large quantities of chloride of sodium or 

 of magnesium, in which it is placed without any transition — an 

 endurance due without doubt largely to its protective integu- 

 ments — permits of the supposition that one would be able, 

 working gradually, to keep it living continually in brackish 

 water when it is adult. Perhaps one would even arrive, in 

 habituating them progressively during a series of generations, at 

 the point of making it accomplish therein the entire cycle of its 

 existence ? This opinion finds great support in the fact that a 

 closely allied species, D. circumflexus, F., normally inhabits both 

 fresh and brackish water. v 



Finally, I much wish that entomologists would make similar 

 experiments upon Dyticus marginalis, to see if their results 

 agree entirely with mine, and upon other aquatic insects with 

 trachsean respiration, for such experiments, made with precision, 

 are useful for the knowledge of the biology of the insects. 



BERGSTRASSER ON THE CLOUDED YELLOWS.* 



The "goats-clover butterfly," or "orange-yellow hay butter- 

 fly," Papilio hyale, L., is a light concolorous Danaid. The 

 name " goats-clover butterfly" (geisstaudenfalter) is made use of 

 by the Viennese entomologists, because the Austrian goats-clover 

 (geisklee) or trefoil forms the food-plant of the caterpillar. This 

 caterpillar may be classified amongst the side- striped larvae 

 (seitenstreif-raupen), of which the above mentioned " Christ's 

 thorn butterfly " (kreuzdornfalter), Papilio rhamni, L., is an 

 example. On account of its colour it is compared to the orange, 

 and is called in France the " hay butterfly," because it makes 

 its first appearance in the hay season towards the end of summer. 



Our illustration (Plate II. figs. 3 and 4) shows the upper and 

 under side of the female. As this butterfly would often be con- 

 fused with the next following, P.palceno, L., Herr Esper gives an 

 accurate description of it. The ground colour is orange-yellow 

 in the upper wings. These are also, in the middle towards the 

 anterior edge, marked with a black spot. On the outer edge it 

 has a broad blackish brown border, with detached bright yellow 

 spots. The fringe is always rose-coloured. In the smaller 

 reddish yellow ground of the lower wings a beautiful orange- 

 yellow spot stands well out. The border is also dark here, as in 

 the upper wings, and likewise distinguished by bright yellow 

 spots ; but it is not quite so broad, and does not extend so far 

 towards the end. On the inner edge the wings are bright yellow, 

 and along the margin greenish. The body is coloured greenish 



* Translated from Bergstrasser's ' Nornenclatur,' 1779, by Mrs. Brown, 

 Rosetield, Elgin. 



