137 



3. Peyssonnelia (Cruorielja) Boergesenii nov. spec. 



Thallus totus adnatus, valde calcarius, superficie levi cum 

 singulis venis conspicuis, e centro ad peripheriam currentibus, 

 constans hypothallo et perithallo. Hypothallus constat filamentis 

 repentibus, juxtappositis, flabella angusta, elongata, efficientibus. 

 Cellula apicalis longa; cellulae filamentorum hypothalli seque altse 

 aut altiores ac cellule apicales. 



In speciminis juvenilibus omnes cellulse filamentorum repen- 

 tium fere eequales, in speciminis adultioribus axis principalis con- 

 spicuus, cellulis majoribus. 



Perithallus divisus in partem inferiorem, cellulis magnis, 

 tetragonis aut l l / z altioribus quam latis, altis 40 36 //, latis 40 

 36 20^ et in partem superiorem, cellulis gradatim decrescentibus. 

 Cellulis periphericis multo brevi- 

 oribus quam latis, altis 10 /^, 

 latis 20/u. 



Nemathecia cum carposporis 

 quadripartitis zonatis, paraphyses 

 cellulis longioribus quam latis, altis 

 40361612 fji, latis 68- 

 12^ et cellulis apicalibus monili- 

 formibus. Nemathecia cum tetra- 

 sporangiis ignota. Thallus altus 

 rh 500 p, nemathecia 240 //. 



Peyssonnelia (Cruoriella) Boer- 

 gesenii 1 } (Fig. 142) distinguishes 



itself by its smooth surface marked with delicate but distinct 

 veins, visible to the naked eye and running in a fan-shaped di- 

 rection from the centre towards the periphery. These veins are 

 quite different from the radial lines, we observe f. i. in the thal- 

 lus of P. rubra and depend probably upon the axis with large 

 cells of the hypothallus. In a dried state the colour of the thal- 

 lus is very striking owing to the greenish hue of the dark purple 

 frond. 



In the collection of Dr. BORGESEN are four numbers from 

 the same locality that I believe belong to this species, though 

 in structure they show some differences, but these differences 

 depend on the age of the individuals. Seen from below No. 1442 



Fig. 142. Peysonnelia Boergesenii 



nov. spec. Surface view of the 



plant. X 1,6. 



I have great pleasure in dedicating this alga to Dr. BORGESEN, the 

 botanist and explorer of the marine flora of the Danish West-Indies. 



