300 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



been named by him Tetramyxa parasitica. He 

 refers it to the Myxomycetes, from the known 

 genera of which it is to be recognised by the 

 spores being formed by quadripartition. The 

 tubers are very likely originated by zoospores 

 being formed on the germination of the spores, 

 the zoospores then penetrating into the tissue of 

 the plant and producing hypertrophy of the tissue^ 

 I cannot find that the species had ever been found 

 in Britain before Mr. Boyd discovered it, so it is to 

 be regarded as a highly interesting addition to our 

 flora. 



V. ON AN ABNORMAL FEMALE 0¥ ACILIUS FASCIATUS. 



In looking over my note-book I find the following 

 observations made in 1876 : " On 27th May, found in 

 Possil Marsh a female Acilius fasciatus with the 

 elytra smooth — as in the male — and almost glabrous, 

 otherwise agreeing with the normal female." I have 

 no reason to doubt the correctness of the above 

 note. Similar instances of female Dytiscus appear- 

 ing with smooth wing-cases have been recorded; 

 and I have seen them quoted as examples of 

 dimorphism, but to my mind the phenomenon is to 

 be explained by atavism — reversion to an earlier 

 condition when both sexes had smooth elytra. 



VI. THE HOTHOUSE THRIPS, HELIOTHRIPS 

 ADONIDUM, HAL. 



This destructive pest is found in our hot-houses 

 on all plants, feeding on the flowers as well as on 

 the leaves. It occurs often on vines, the leaves of 

 which it causes to become blotched and spotted, and 

 ultimately sucks all the substance out of them, so 

 that the plant dies. The eggs are laid on the 

 under side of the leaf; the larva is white or 

 yellowish, the colour of the abdomen varying with 

 the amount of food in it. Haliday describes the 

 abdomen in the imago as reddish only at the tip, and 

 this no doubt is the case with most of the specimens ; 



