No. 3] REMARKS ON NORTHERN LITHOTHAMNIA. 57 



cies in question. Be it said that I have also seen specimens with 

 thicker crusts, a state of things pointed out also by Dr. Rosen- 

 vinge 1. c. Besides 1 have seen specimens of L. glaciale which 

 have partly developed almost similar, though shorter, branches. 



Lithotli. tophi forme occurs under the same conditions as L. 

 soriferum, frequently forming small banks, now alone, now asso- 

 ciated with other species. Like L. soriferum, it is apt to be co- 

 vered with Lithotli. flavescens and Phym. investiens. The alga 

 is fructiferous in the months of March and of June — September. 



As to the geographical distribution of the species is to be 

 observed that the occurrence in the White Sea, stated in Norw. 

 Lithoth. p. 126, is likely to concern the species in question in the 

 sense now taken. I have seen no sporangia. Some specimens 

 have been collected in the Bay of Founday, Nova Scotia (by 

 Ruggles, comm. Mackay, no. 12) which have no doubt to be 

 referred to L. tophiforme. They were collected together with L. 

 glaciale (Mackay, no. 9 and 10) and bear the same relation to 

 the latter as the specimens from northern Norway and from Scot- 

 land mentioned above. One of these specimens bears a few con- 

 ceptacles, which are 400—500 fi in diameter and contain bisporic 

 sporangia. Besides, I have some specimens from Eastport, Maine, 

 dredged by Mr. Lyman and kindly communicated to me by 

 Professor Far low (no. 5). I formerly considered these specimens 

 as extreme forms of L. glaciale. Unfortunately they are sterile, 

 but they now seem to me to have to be referred to L. tophi- 

 forme. One of them is most nearly connected with f. sphcerica, 

 but the branches are shorter and more coalescing than in typical 

 specimens of this form. The others are more connected with 

 Greenland specimens of f. divergens, though with shorter branches 

 than usual. 



As to the distribution of each form, is to be observed that 

 f. shpcerica occurs in several places at the northern coast of Nor- 

 way. A single specimen, probably belonging to this form, is known 

 trom Julianehaab on the west coast of Greenland 1 ), and besides 



*) This specimen is that mentioned by Dr. Rosenvinge I. c. under L. 

 soriferum f. globosa (no. 423 b). Once I thought it referable to L. JJngeri 



