No. 1 1] PLIOSTROMA A NEW SUBGENUS OK MELOBESIA, ' 7 



layers of cells and attains a thickness of up to 150 //, though 

 usually less. Cp. 1. c. The conceptacles of sporangia here men- 

 tioned represent in faet — as I observed in Alg. Not. V p. 17 — 

 conceptacles of cystocarps. The species occurs at the Bahamas 

 (Howe) and at St. Croix in the West Indies (Børgesen!). 



llie foUowing species are still to be kept under Carpolitlion, 

 subgenus of Lithophyllum, with a single layer of basal hypothallic 

 cells and several layers of perithallic cells: 



Lithophyllum tasmanicum Fosl. 

 „ paradoxum Fosl. 



„ jugatum Fosl. 



