F. Børgesen: Rhodophyceæ of the Danish W. Indies. 



139 



Fig. 144. Peyssonnelia Boergesenii no v. 



spec. Section through dried margin of 



thallus. t. topcell. (380 : 1). 



cells higher than broad, di- 

 minishing regularly towards 

 the periphery, the peripheral 

 ones being the shortest of 

 all: height 10 fi, breadth 20«. 

 This succession is, however, 

 not always so striking as 

 told here. 



The frond can easily 

 attain a thickness of 500//, 

 even more, for my sections 

 do not run through the 

 thickest part of the frond. 

 The cells contain much gra- 

 nules, that take at first a golden brown colour by hydrochloric zink- 

 iodine and become almost black under long influence of the reagens. 



I have only seen 

 one nemathecium with 

 carpospores. It had 

 a darker colour than 

 the frond, was ele- 

 vated above its sur- 

 face and irregular in 

 form ; it had a height 

 of 240 /i and the qua- 

 dripartite, zonate car- 

 pospores of IQOfjt, but 

 these looked as if they 

 were not yet quite 

 ripe. The paraphyses 

 ended in a short, round 

 cell, not in a broad 

 blunt one (Fig. 145, a). 

 Nemathecia with 

 antheridia were more 

 frequent ; I found 

 them on the same 

 plant as the carpo- 

 spores (Fig. 145 c). 



This Peyssonnelia 

 resembles P. Harvey- 

 ana very much with 





røDfl 



Fig. 14.5. Peyssonnelia Boergesenii nov. spec. 

 a. section through nemathecium with carpo- 

 spores ; b. section through thallus in transverse 

 direction; the inferior cells are sometimes larger 

 when the section hits upon a principal axis of 

 the hvpothallus; when the section is made in 

 longitudinal direction the inferior cells ascend 

 obliquely. (250 : 1). c. section through nemathe- 

 cium with antheridia. (540:1). 



