36 



by essential characteristics. It apparently sometimes even approaches 

 L. incrusians f. Harveyi in habit. 



Habitat. Unknown to me. The specimens found with us 

 are picked up from the sublitoral region, or found washed ashore. 

 It bears sporangia in summer. 



Occurrence. Only known from the most southern part of the 

 coast, gathered at Mandal (Wille) and at Kragero. 



Geogr. Distribution. Britain (Johnston, Harvey, R. N. 

 Tel Ian); the Atlantic coast of France (Crouan)? The Mediter- 

 ranean Sea (Philippi); the Adriatic Sea (Hauck). 1 ) 



Lithothamnion fornicatum Fosl. 

 Contrib. II, p. 3; excl. var. 



f. typica Fosl. mscr. 



Descr. Lithothamnion fornicatum Fosl. 1. c. ; excl. var. 

 Fig. „ „ „ „ t. 2 (non t. 1). 



f. robusta Fosl. mscr. 



f. ramis subcylindricis vel saepe parum incrassatis, 3—5 mm. 

 crassis, apicibus obtusis vel interdum truncatis. Tab. 9. 



Addition to the description of the species. I recorded 1. c, 

 that the conceptacles of sporangia in this species do not grow 

 down into the frond. I then examined several specimens destitute 

 of grown-in organs of that kind. Later, however, I found such 

 ones in small number especially in the form robusta, but also in 

 f. typica, although they appear frequently not to be found. This 

 may partly depend thereon, that probably old specimens of the 

 plant in all rather seldom develop reproductive organs, partly that 

 the conceptacles of sporangia apparently do not occur in the same 

 individuals bearing those of cj^stocarps, which do not become over- 

 grown. Besides, the whole roof of the conceptacles of sporangia 

 seems easily to fall awa}^ although they are very little prominent 

 and the roof apparently nearly as thick as in L. fruticulosum, and 



*) After this was in the hands of the printer I got some Lithothamnia from 

 Mr. P. Hariot of Paris, gathered on the coast of California. Among these 

 is a specimen of the present species, according with Adriatic specimens of 

 f. typica. It will be recorded in a separate paper. 



