298 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



III. ABUNDANCE OF THE GALLS OF NEUROTEBUS 

 IN 1884. 



All over Clydesdale during the autumn of 1884 

 the galls of Neuroterus were excessively abundant — 

 especially those of N, baccarum (lenticularis). In 

 many localities the roads were covered with them^ 

 while in other places they were heaped up by the 

 wind into piles. Many leaves were entirely covered 

 with them, not a part being left without a gall. 

 On the other hand, in those places where N. lenticu- 

 laris was especially abundant, the galls of Neuroterus 

 ostreus and of Biorhiza renuvi were conspicuous by 

 their absence, or by their extreme rarity. As the 

 spring forms of these two species were as abundant 

 as usual, I can only account for their scarcity 

 in the autumnal brood by the fact of their 

 being crushed out by the commoner N. lenticularis 

 occupying the leaves so much, and thus not leaving 

 any room for the galls of the species just mentioned 

 to reach maturity — the commoner species, in fact, 

 pushing them out. If this is the correct explana- 

 tion, then we have here a good instance of how 

 species may become scarce, if not extinguished. It 

 would be of interest to know if the spring forms of 

 N, ostreus and B. renum were scarce in 1885. 



IV. ON FUNGOID GALLS. 



On some plants certain fungi form structures which, 

 so far at least as outward resemblance goes, have 

 every appearance of being true galls. Of these I 

 have met with three kinds in the West of Scotland, 

 which, I think, are worthy of notice: 



1. On Rhododendron ferrugineum, — The fungoid 

 galls on this plant are found on the leaves, have a 

 long diameter of from 3 to 6 lines, are irregular in 

 shape (usually irregularly oval), smooth and reddish 

 externally, internally whitish and spongy in texture. 

 I have only found myself one gall on each leaf. 

 This gall has been described by Albert Miiller {Gard. 

 Chron., July 29th, 1871) as the work of an insect. 



