M. FOSLIE. [1900 



L. rugosum Fosl. 



Calc. Alg. Fuegia p. 66. 



f. genuina. 



L. rugosum 1. c. 



f. valida Fosl. mscr. 



The crust about 3 mm. thick, with crowded and rather ana- 

 stomosing, simple or subsimple branches about 10 mm. long and 

 3—6 mm. thick. 



f. crassiuscula Fosl. mscr. 



The crust about 2 mm. thick, with knotty and rugged sur- 

 face or rather densely crowded excrescences or short branches 2 — 4 

 mm. thick. Conceptacles of sporangia convex but very little pro- 

 minent, 350 — 400 jjl in diameter. 



The form valida differs from the typical form by thicker crust 

 and coarser branches which besides are more anastomosing than 

 in the latter. In structure it accords in the main with the said 

 form, and so also with reference to the conceptacles of sporangia 

 except that the latter are not always so decidedly disk-shaped in 

 f. valicla, but sometimes only the central parts being flattened. 

 This form rather approaches L. bracliyclaclum in habit, and on 

 the other hand in part also Litliophyllum grumosum. 



It is as yet uncertain whether f. crassiuscula is to be consi- 

 dered a form of the above species, or a separate species. I have 

 seen but a solitary well developed specimen, and at any rate 

 being closely related to L. rugosum I provisionally adopt it a 

 form of the latter. It forms an about 2 mm. thick crust which 

 is knotty and rugged, or in a somewhat advanced stage develop- 

 ing numerous more or less densely crowded excrescences or short 

 and often rugged branches 2 — 4 mm. long and of about the same 

 thickness, occasionally confluent. New crusts are formed upon 

 the primary, or scaly thickenings here and there are formed. 



In structure it shows an almost coaxilate development, with] 

 elongated but rather narrow hypothallic cells up to about 25 fi\ 

 long. The cells of the perithallic layer are rather varying both in 

 shape and size. They are partly square or rounded, 5 — 9 ;j- in 

 diameter partly vertically elongated and up to l 1 / 2 or occasionally 



