AT THE MICROSCOPE. 251 



Columbarins^ described by him in the " Annals of Natural His- 

 tory^^ Vol. 5, p. 242, which has also occurred in Dovecotes, near 

 Leeds {Mon. A7iop. Brit, p. 173). 



Here is interesting work for the microscopist indeed. I do 

 hope some of our members may be induced to take it up, and 

 will favour us by '■^passing them rounds 



The only specimen I have of this species was taken off a 

 pigeon which fell dead (shot, probably) in the little garden at- 

 tached to the house I was then residing at, in Queen's Road, 

 Dalston, now some 30 years ago. I just mention this as some 

 little encouragement to those who have to work under difficulties, 

 as, it must be admitted, Londoners have in some respects. 



Pupa-case of Ephemeron.— The slide I myself enclose is illus- 

 trative of one stage in the metamorphosis of a small species of Ephe- 

 mera, or May-fly. These occur in myriads for a portion of the 

 summer near two large sheets of water, called, in the homely 

 phrase of the place, " Frensham Great Pond " and " Frensham 

 Little Pond." They are favoured resorts of many aquatic insects. 

 A person walking near these lakes when the insects in question are 

 coming out, may find him or herself quickly covered with the small 

 May-flies, which settle, remam tolerably quiescent for a time, then 

 wriggle out of their old suit of clothes, and fly away in a brand 

 new one. A graphic description of the process will be found in 

 Westwood'' s " Introduction to the Modern Classification of Lisects^^ 

 vol. 2, p. 27, and in a foot-note a discussion of the nature of the 

 metamorphosis. 



A discussion of the matter, specially as a microscopic study, 

 by the present writer, will be found in the " Trcmsaction of the 

 Micro. Soc. of London,'' Vol. for 1866, pp. 69, 70, and PI. VIL, and 

 J. W. Lubbock has discussed it in Clocon dimidiatu7n, in the 

 pages of the Linnean Transactions. 



TuFFEN West. 



Sting of Scorpion.— I read with interest Tuffen West's remarks 

 about this and the oxalic acid crystals, or isomeric crystals. He 

 suggests that '' the fangs of Poison Serpents might be expected to 

 yield similar crystals." 



Some years since, when examining the structure of sections of 

 teeth-dentine and enamel by polarised light, my brother, F. H. 

 Balkwill, supplied me with a poison-fang of a viper ; this I pro- 

 ceeded to make a section of, in the course of which I observed 

 that it was a tube with a small oval aperture, near or at the apex, 

 I think the former, and that it was filled with semi-transparent, 

 sub-quadrangular, or cubical granules. Unfortunately, I carried 



