38 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



IV. 

 ON THE HABITS OF EUURA (olim CryptocampusJ. 



BY P. CAMERON, V.-P. 



[Read 27th November, 1S83.] 



The immortal Swedish Naturalist De Geer was the 

 lirst who described the economy of any species 

 of Euiira. He gave* a full account of the species 

 now called Eiiura pentandrce, so named from its 

 frequenting the willow Salix ijentandra. This 

 species forms large, irregular, woody galls on the 

 young shoots ; in size they vary, some being not 

 much larger than a small cherry, while others reach 

 the size of a large walnut. They are essentially 

 medullary galls, that is, they take their origin in 

 the pith, the swelling gradually extending to the 

 woody portion of the twig. When fully formed 

 they consist of a spongy central mass representing 

 the pith, and of a larger outer wall of woody 

 matter, composed of very much distorted cells. 

 Inside of this formation the larvae live, feeding 

 chiefly on the pithy cells, and to a less extent on 

 the inner part of the woody stratum. Several 

 larvae live in a single gall ; the largest number I 

 have noticed was seven, the smallest, two. The 

 cocoons are spun in the centre, among the debris of 

 the pith and frass, and in these cocoons (which are 

 formed in the autLimn) the larvae remains un- 

 changed till the following May, when they moult, 

 become pupae, then in fourteen days or so enter 

 the perfect state, emerging from the galls in June. 

 The same, or a very closely allied species, forms 

 similar galls on the poplar. 



The habits of the other two recorded British 

 species, angusta and saliceti, appear to be but very 

 *M&nioirs, ii. p. 271, No. 24, Taf. 39, Figs. 1-U. 



