HYPOCRBLLA AND ASCHBRSONIA. 191 



or, more rarely, by Aschersonia placenta. Asckersonia hadia 

 usually occurs with Hypocrella Mollii. In all these cases 

 there is little doubt that the fungi are parasitic on the same 

 species of insect. 



There may, of course, exist cases in which a particular 

 species of fungus is confined to one species of insect, but no 

 evidence in support is as yet available. 



DiSTBIBUTION. 



The material of these genera in herbaria is, as a rule, 

 remarkably scanty. One would imagine that in many cases 

 the fungus has been accidentally gathered on phanerogamic 

 specimens collected for distribution, and discovered subse- 

 quently in the herbarium. Types frequently consist of a 

 single leaf bearing only two or three examples of the fungus, 

 and in many cases the fungi on the leaf belong to more than 

 one species. It is not to be wondered at, therefore, that in 

 the case of the commoner species the list of synonyms is some- 

 what lengthy, since the material from which the species was 

 described is often insufficient to give any idea of its range of 

 variation. 



The examination of the herbarium collections would lead 

 to the conclusion that species of these genera are rare. But 

 it is not difficult, according to Ceylon experience, to collect 

 large numbers of a species, provided one devotes the time to 

 it. Of course, cases do occiu' when a single specimen is found, 

 and a thorough search fails to reveal more, but, in general, 

 the systematic examination of a bush or tree on which a 

 specimen has been found will result in the discovery of dozens, 

 or even hundreds. It has to be remembered, however, that 

 the fungus is parasitic on a scale insect, not on the plant, and 

 its parasitism is not specialized. Consequently, a collection 

 from one plant, even if all on the same scale insect, may 

 include several species of Aschersonia or Hypocrella. 



These genera are essentially tropical, no species being 

 known from temperate climates. Several species are found 

 in Florida, but the majority occur within the tropics. 



With two exceptions, one of which is doubtful, the species 

 of the Western Hemisphere are distinct from those of the 



6(9)21 (26) 



