95 



of all. They are long, filamentous, consisting of a 

 single series of loculi, and originate from the base of 

 assimilative filaments. In Leptonema certain of the 

 upper cells of the filaments become the mother-cells 

 of the plurilocular sporangia. These cells bulge out 

 laterally and divide into 3-6 transverse loculi, each 

 with one or two gametes. In Halothrix the matter 

 is more complex. The mother-cell divides up into a 

 considerable number of cells, of which those at the 

 periphery grow out into rows of loculi which contain 

 each a single gamete. Giraudia, of which the gametes 

 have been observed to conjugate, possesses two sorts 

 of plurilocular sporangia. The one kind are tapering 

 filamentous bodies of several rows of loculi, otherwise 

 resembling those of Elachista in origin. The other 

 kind are of singular appearance, originating from the 

 cells of the assimilative filaments by transverse and 

 radial divisions, and forming clusters of ovate pluri- 

 locular sporangia, each of several rows of loculi. This 

 second kind approaches the Halothrix type in general 

 character. 



The Geographical Distribution of the Elachistacece 

 is general, but most of the forms are from the North 

 Atlantic. Elachista, Halothrix, Giraudia, and Lepto- 

 nema are British. 



The genus Myriotrichia (North Atlantic), of which 

 M. clavce/ormis is British, stands in a somewhat 

 isolated systematic position. It has been placed 

 with the forms ranged under Encwliacece, and in a 

 separate position by itself as the type of an order 

 Myriolrichiacecc, while its relationship with Elachis- 

 tacecc is not denied. Further research, not so much 



