Abstract:
'l'he species discussed in the ensuing pages, except P. dispar von Linst., 1904, comprise some of the material which has from time to time been sent to this institute for determination. As this genus
comprises a considerable number of species, and as the writer has found the accompanying key to be of considerable help in his determinations, he has thought it advisable to place this key at the
disposal of other workers, and at the same time give a description of those new forms which he has been able to study.
