180 [AugUBt, 



Archiv, 1855, " Zuui feinereu Bau der Arthropoden," are of interest 

 and importance, and I am glad to be able to show a woodcut from his 

 paper, illustrating the skin and skin glands and hairs of the Bomhijx 

 ruhi. 



After careful consideration of the case under my care, and those 

 previousl}'^ published, I am of opinion that the symptoms and course 

 of the disease can only be adequately explained by assuming that they 

 are due to the action of a specific poison contained in the hairs, or 

 possibly resulting from their disintegration in the tissues. The nature 

 of this poison is quite unknown. 



[Mr. Lavvford has kindly furnished iiie with the foregoing notes ; it seems some- 

 what strange that the hairs of Cnethocampa processionea should have a less effect 

 than those of Bombyx ruhi ; the explanation, however, is apparently to be found in 

 the fact that the eye was struck violently by the larva of B. ruhi ; the injury done 

 by the hairs appears to be in part mechanical, and in part due to poison. Lord 

 Walsingham, who has carefully examined the hairs of C. processionea , says that 

 besides the longer hairs there are tufts of smaller ones, each of which is furnished 

 at the side with projections, and these work into the skin by the base, not the tips, 

 with an action like a corkscrew. — W. W. F.] 



ON EXCEPTIONAL OVIPOSITION IN PYRRHOSOMA MINIUM, 



HARRIS. 

 BY ROBERT McLACHLAN, F.R.S., &c 



In this Magazine, vol. xxi, p. 211 (February, 1885), I gave a note 

 on females of Agrion onercioriaJe, found during an excursion in Savoy 

 in July, 1 884, having their abdomens incrusted with white mud through 

 ovipositing in places where the water was nearly dried up. Accoi'ding 

 to an observation made recently, this habit obtains in other species of 

 Agrionina. Early in June, 1868, I found A. mercuriale near Lynd- 

 hurst in the New Forest, but have never since seen it alive in this 

 country. Being in the Forest last week I was prompted to try again 

 for the insect ; the precise locality of my captures 27 years ago was 

 110 doubt re-discovered, but the Agrion was not to be seen. Pyrrhosoma 

 minium was, however, abundant in a deep drain or ditch in which the 

 water was nearly dried up. Some of the females having a peculiar 

 appearance I caught them, and found the peculiarity to be caused 

 by precisely the same conditions observed in the Agrion in Savoy 

 in 1884, the abdomens being incrusted with dry whitish mud from 

 the tip up to the 1st or 2nd segment. In one individual nearly 

 the whole body (including the wings) showed traces of mud, in- 

 dicating that she had probably descended entirely beneath the 



