A Revision of the Tricliiaeese. By G. Massee. 327 



violet or brownish- violet ; Lamjarosporse, spores variously coloured, 

 usually some shade of yellow, but never violet. These primary groups 

 are each again divided into two sections, Atrichse, sporangia without 

 a capillitium, and Trichophorse, sporangia furnished with a capillitium. 

 The Trichiacese belong to the Lamprosporse, section Tricliophorm, 

 and the leading characteristic of the family consists in the spirally 

 arranged ridges on the elaters or threads forming the capillitium. 

 The species are all minute, not exceeding 4 mm. high, generally very 

 much less, but, owing to the gregarious habit, are often conspicuous 

 objects, especially after dehiscence, when the bright yellow spores of 

 most species cannot fail to attract attention. The most usual habitat 

 is decaying wood, where most species pass the vegetative period, and 

 from which in all probability their food is obtained, but during the 

 commencement of the reproductive stage, the motile plasmodium fre- 

 quently creeps to the surface, or even passes on to living leaves, &c., 

 where the sporangia are formed. Eostafinski first suggested the 

 worthlessness of external form in the discrimination of species, and 

 accordingly his species are distinguished by the microscopic characters 

 furnished by the spores and capillitium when present, and the question 

 arises as to the relative value of the form of the sporangium and 

 presence or absence of a stem on the one hand, and the microscopic 

 characters of the capillitium and spores on the other. It is perfectly 

 true that if we adopt the form of sporangium and presence or absence 

 of stem as the primary idea in determining species, we must ignore 

 the microscopic features ; whereas if the structure of the capillitium 

 and spores constitutes the basis of classification, then we bring together 

 forms in which the sporangia are sometimes of a definite form and 

 seated on a distinct stem, in other instances sessile, and sometimes very 

 irregular in shape and forming shapeless conglomerations ; nevertheless, 

 the sequence from one shape of sporangium to another is in numerous 

 instances, even in the same cluster, so very evident, that in all pro- 

 bability, Eostafinski's idea, although not altogether satisfactory, is the 

 best known, and has been followed in the present paper. A very 

 constant sequence of development in the ornamentation of the epispore 

 is evident in every genus belonging to the family under consideration, 

 which is as follows :— (1) species with the epispore smooth ; (2) species 

 with the epispore rough with rounded warts ; (3) species having the 

 epispoi-e with slightly elongated raised hands, the surface of the raised 

 lands plain; (4) the raised bands as in (3), but having the surf ace of 

 the hands ornamented with minute pits ; (5) species having the epi- 

 spore with elongated and curved raised hands that remahi distinct 

 from each other, surface of raised hands plain; (6) species with 

 bands as in (5) but surface of hands with minute pits ; (7) species 

 having epispore with raised hands anastomosing to form a more 

 or less regular polygonal network, surface of hands plain ; (8) species 

 with the epispore having bands as in (7) but surface of hands ivith 

 minute pits. This peculiar sequence of spore ornamentation is not 

 confined to the Myxogastres, but is also present in other groups of 



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