No. 6] NEW MELOBESIEAE. . 23 



Fosl. and on the other M. confervicola (Kiitz.) Fosl. It much 

 resembles the former in habit, but differs especially as regards the 

 conceptacles as well as in structure, and so also in part as regards 

 the latter but hitherto not well known species. 



The present species is only known from Bermuda. Herb. W. 

 G. Far lo w, no. XXVII. 



M. Cymodoceae Fosl. mscr. 



Thallus at first forming almost orbicular, afterwards confluent 

 patches of irregular shape and extent on the leaves oiCymodocea, 

 composed of a solitary layer of cells except in the neighbourhood 

 of the conceptacles. Conceptacles of sporangja partly solitary, 

 subhemispheric or subhemispheric-conical 200 — 280 y. in diameter, 

 partly confluent in short streaks or small whorls. Sporangia four- 

 parted, 110 >j- long by 55 \i.. 



In a 3 r oung stage the species forms scaly, almost orbicular or 

 sometimes reniform patches which in a more advanced stage often 

 are crenate or irregularly lobed, afterwards more or less confluent 

 and of indefinite extent, frequently however with rather visible 

 limits between each crust. The one crust sometimes stretches itself 

 over the other, or cuniform between each other, and at length 

 almost covering the leaves of the host. The colour is in a dried 

 state greyish with a rosy shade, or light rosy. 



On a vertical section the basal cells are up to about IV2 times 

 higher than broad, or 10 — 12 by about 7 ,u, with rather thick 

 walls. Seen from above the cells are in the monostromatic part 

 12 — 18 i-t long and 8 — 12 y broad, with small cortical cells. 



The conceptacles of sporangia are much varying in external 

 appearance, occupying the greatest part of the crust, partly soli- 

 tary but frequently crowded, subhemispheric or subhemispheric- 

 conical, 200 — 280 ;j- in diameter, partiy and more frequently con- 

 fluent, forming short streaks on the surface of the frond, or very 

 often small whurls composed of 4—6 confluent conceptacles looking 

 like a large and solitary one with depressed centre, or now and 

 then small flattened wartlike prominences reminding one of a rather 



