io8 BRITISH GALLS 



Tyknchus Davainii causes galls on Mosses; usually the 

 terminal internodes remain closed, and the bunch of leaves 

 forms a terminal artichoke-like gall. Dixon, in 1905, re- 

 ported its occurrence in Eurhynchium Swartzi Curnow, and 

 also recorded that Thamnium {Porotrichum) alopecurum Linn,, 

 bears galls caused by an unknown species of Tyknchus. He 

 considered that galls of this nature appear to be very un- 

 common on Mosses — as he rarely came across them among 

 the many thousands of specimens that passed through his 

 hands in twenty years or more. Mr. W. E. Nicholson, 

 however, has informed me quite recently that in his ex- 

 perience such galls are not very uncommon in this country. 

 He kindly sent me sonie flypnum cupressifonne gathered 



Fig. 24 — TylenchusDavamiiBasti3.il. Female. (32,1.) 

 Fig. 25 — Tyknchus Davainii. Male. (32/1.) 



on the Downs near Lewes which contained eelworms, 

 apparently Tyknchus Davainii, in large numbers. The 

 galls were terminal, each about 2 mm. long. Nicholson 

 thinks there can be little doubt that these galls are 

 often overlooked. " On the Hypnum they might easily be 

 passed over. They affect the mosses prejudicially, and 

 they are consequently unlikely to be found on specimens 

 gathered for herbarium purposes." He also noted the occur- 

 rence of Nematode galls on the hepatic Harpanthus scutatus 

 received from West Inverness. Schiffner has recorded the 

 occurrence of these eelworms on many Mosses on the Con- 

 tinent. There are also Continental records of hepatics 

 attacked by eelworms, presumably this species. 



