70 M. FOSLIE. U905 



rather impressed, with an annular border somewhat elevated, re- 

 presenting the peripherical portion of the roof. The central part 

 is traversed by about 30 — 40 muciferous canals. All the concep- 

 tacles of sporangia examined have been attacked by animals and 

 are destitute of sporangia. The said conceptacles are rather re- 

 sembling those of L. foecundum as well as those of Ph. poly- 

 morphum, and are finally overgrown. Those of cystocarps are 

 not yet known, and, therefore, it is as yet questionable how to 

 place the species systematically. 



As to the synonymy is to be observed that Millepora in- 

 formis Lam. is more likely to belong to the species in question 

 than to Phym. polymorphum. to which it is referred in Syll. Alg. 

 p. 1724. By the kindness of Dr. C ha Ion, I have had the op- 

 portunity of examining specimens of L. calcareum f. mamillosa, 

 determined by Mr. Heydrich, and admitted by Dr. Chalon in 

 Liste Alg. 1. c. These specimens represent a stunted form of L. 

 fruticulosum, recalling stunted forms of L. calcareum f. coralloi- 

 des — compressa worn by friction. They are, however, provided 

 with conceptacles consistently with those in L. fruticulosum. It 

 seems as if f. mamillosa is considered by Mr. Heydrich as being 

 identic with L. mamillosum Hauck (Goniolithoyi mamillosum 

 Fosl.), a species quite different from both the mentioned ones. 

 These specimens are in part covered with crusts of Lithoth. Sonderi 

 and Phym. polymorphum. 



L. calcareum is easily recognized, when provided with well 

 developed conceptacles of sporangia ; but specimens stunted or 

 faintly developed are easily confounded with L. fruticulosum. On 

 the coast of France and in the Mediterranean it sometimes grows 

 gregariously with the said species, or is even found coalescing 

 with it so as to make it sometimes difficult to draw the limit. 

 Cp. Lithoth. Adriat. Meer. etc., p. 32 and pi. II, fig. 24—26. Mon- 

 strous specimens sometimes even approach certain forms of L. 

 glaciale. Cp. 1. c. pi. Ill, fig. 1—7. On the other hand, the alga 

 often resembles L. norvegicum in habit, particularly delicate forms 

 of f. squarrulosa approach f. pusilla, and f. subsimplex may be 

 hardly distinguishable from a coarse f. similis of the said species. 



