245 



trichogynes penetrating through the osliole. As to tlie structure of the procarps, my 

 observations are so incomplete that 1 must content myself with referring to the figures 

 without any interpretation. The bottom under the female conceptacles was composed of 

 one to three layers of cells. Ripe cystocarps in good condition were not met with; 

 they seem to be rather similar the tetrasporangial conceptacles. 



As will be seen from the above description, this species differs from M. Lejolisii 

 principally by the structure of the polystromatic frond, by the shape of the spor- 

 angial conceptacles, by the normal presence of a columella, by the two-spored 

 sporangia, and seemingly by the formation and shape of the spermatia. 



Locality. Sa: On Zostera-lenwes at Horsens, September 1893. 



3. Melobesia limitata (Foslie) K. Rosenv. sp. nov. 



Melobesia Lejolisii Rosanoff f. limitata Fosl., Remarks 1905 (190G) p. 102. 



In his valuable paper on the northern Lithothamnia (Remarks, 1905 (1906) 

 p. 102) Foslie described a forma limitata of Melobesia Lejolisii, characterized prin- 

 cipally by smoother and apparently more solid crusts, and by less crowded con- 

 ceptacles, frequently a little higher and somewhat pointed or subhemispherical- 

 conical, and more sharply defined. He referred to it almost all the Danish speci- 

 mens noted under the species mentioned but 

 growing on Algse instead of on Zostera. In 

 examining these specimens, I have found that 

 they not only differ in the characters named by 

 Foslie, but that they must be regarded as 

 representing another species distinct also in 

 several other characters. 



The crusts have a diameter of 3—4 mm, 

 sometimes they reach 5 mm or more. They 

 are more or less irregularly orbicular with 

 lobed margin. Frequently several crusts 

 are confluent. The frond may be mono- 

 stromatic from the border to the concep- 

 tacles, or the inner part may be distromatic 

 (figs. 166, 167) or even thicker (fig. 163 D). 

 When seen from the face, the frond pre- 

 sents a similar aspect to M. Lejolisii, but the 

 cells are usually somewhat longer, viz. 



Fig. 163. 



Melobesia limitata. A-B, marginal parts of frond, 

 seen from the face, from M ; .1, before, B. after de- 

 (7 — )8 — 10,5( — 12) /;! broad, Vj-i to 2 times calcification andistaining. C and /J. vertical sections 

 , .1 1 1 m 1 r . of fronds, from I, D from the central part 350:1. 



longer than broad. Transversal fusions 



sometimes occur. The cortical cells are longer in transversal than in radial direc- 

 tion. Trichocytes usually occur; they may be cells situated under a ramification 

 or ordinary intercalary cells in the radiating filaments. They usually lack cortical 

 cells, but such may occasionally be produced (fig. 163 A at left). 



