Last year Dr. Sharp described a species of Trygæus in the »Notes from the Leyden Museum” and made some observations on the probable geographical distribution of the genus, and as I have just obtained another species from Siam, which also requires description, it seems to me appropriate to bring it to notice through the same medium. Although this is the third species only at present described, I believe Mr. Fry has more than one species in a collection which is part of the material lately gathered in the Oriental region by Mr. W. Doherty. When I was in Japan I found Trygæus princeps Sh. in April and May by sifting out masses of damp leaves which had accumulated in the forests or been swept together by the caretakers of temple grounds, and sometimes amongst marsh-refuse. But later in the summer single examples were often obtained by beating foliage, and it is perhaps by this latter method that the few specimens brought home by travellers have been taken.