576 



[December 



B. Gall a deformation and swelling of the twig itself. 

 1. Gall monothalamous, solitary, woody. 



a. Gall oval, growing always at the tip of the twig, 

 but always including several of the sub-termi- 

 nal buds, which are usually aborted, the termi- 

 nal one always. 



b. Gall generally oval, generally growing some dis- 

 tance from the tip of the twig and but rarely in- 

 cluding even a single bud, occasionally at the 

 tip, when it includes only the terminal bud, 

 which is then more or less aborted and occa- 

 sionally obliterated. 



8, S. siliqua n. sj:). ? 

 on S. humilis. (S. 

 cordata? and S. 

 discolor?) 



S. nodulus n. sp. 



on S. longifolia. 



2. Gall polythalamous, woody, growing not far from the tip of the twig, 

 each cell excavated at the origin of a bud, and opening outwards through 

 that bud, wliich is deformed so as to form part of the cell. 



a. Gall oval and bulging, the twig where it grows ] 10, S. triticoides n. 



being enormously contracted in length. 



Gall cylindrical and not bulging, the twig where 

 it grows not being very much contracted in 

 length. 



Gall polythalamous, more or less spongy, with its 

 cells all internal. 



j sp. on S. cordata. 



11, S. hordeoides n. 



sp. on S. liumilis. 



12, S. batatas n. sp. 

 on S. humilis, (S. 

 cordata ? and S. 

 discolor?) 



Gall growing out of the leaf, the shape and structure of the leaf still plainly 

 perceptible, monothalamous, but several of them often confluent. 



1. Growing sparsely from the midrib or one of the prin- 1 13, S. verruca n. sp. 

 cipal veins. I on S humilis. 



2. Growing very numerously from the general surface ] 14, S. semen n. sp. 

 of the leaf. J on S. nigra. 



D. Gall growing from the flower-catkins (and sometimes ~ 

 from the leaves?) and destroying all vestiges of their 

 structure, so as to appear like the crumpled mass of 

 aborted flower-buds in a common cauliflower. 



15, S. aenigman. sj). 



Putting the gall out of the question, and looking only to the insect 

 in all its states, the species 1, 2, 4, 5 and 8, which resemble one ano- 

 ther so closely, that several of them are undistinguishable in the imago 

 state, not only in the dried but in the recent specimen, may be separated 

 as follows. Xos. 3, 6 and 7 belong to the same group as 1, 2, 4 and 5. 

 but. as they are not known to me in the imago, are necessarily omitted 

 here. I find that certain Lepidopterists repudiate the idea, that it 

 is possible for two species of insects, like the two Halesidota referred 

 to in a previous Article, to be undistinguishable in the imago, and yet 

 perfectly distinct in some of their other states. The study of the genus 



