58 



others. It is, as remarked above, nearly connected with L. cras- 

 sum, but shows closer affinity also to the other named species, 

 as well as L. glaciale in habit, and sterile specimens are some- 

 times not easily separated from the latter. The form intermedia 

 may especially in a younger stage even be confounded with L. 

 colliculosum. The distinction between the present plant and L. 

 divergens, L. apicalatum and L. dimorphum will be quoted under 

 the named species. 



I have seen three authentic specimens of L. mamillosum 

 Hauck, Meeresalg. p. 272, which I propose to name L. Hauchii 1 ), 

 a species closely related to L. fruticulosum in habit, and probabry 

 sterile specimens may often only with difficulty be separated from 

 the typical form of this. Cp. Hauck 1. c. t. 5, fig. 1 and 5. 

 However, it appears to be somewhat coarser, the apex of the 

 branches sometimes råtner acute and also showing some diversities 

 of structure, the latter apparently coarser than in L. fruticulosum. 

 Specimens bearing cystocarpic conceptacles are identified at a glance. 

 These organs I found in the named specimens commonly to be 

 500 — 800 ft in diameter at the base, sometimes a little more, and 

 of a considerable height. Hauck 1. c. quotes them in general 

 being about 1 mm. in diameter. The elongated tip seems to fall 

 easily away, and then the conceptacles look rather low, though 

 still higher than in L. fruticulosum. Besides, I found some other 

 in shape similar conceptacles only about 300 ;j- in diameter, which 

 perhaps are those of antheridia. Conceptacles of sporangia appear 

 to be unknown. 



Habitat. The plant lives in the upper part of the sublitoral 

 region, on a depth of 1 — 10 fathom. It prefers sheltered places 

 and rather hard bottom, partly more scattered (especially f. inter- 

 media, f. nanå, f. glomerata, f. corymbiformis) partly abundant 

 or in great masses (especially f. typica, f. fastigiata and partly 

 also f. fiexuosa), not seldom in sounds with strong currents. 

 Sporangia-bearing specimens have been tåken in June, July and 



*) Gu mb el, Die sogen. Nullip. p. 41 records a fossil Lithothamnion by the 

 name of L. mamillosum and, therefore, I propose the species to be named 

 after the late Dr. F. Hauck. 



