489 



material of tliis genus, and ns may be seen, in the definition of ils 

 species I have chiefly followed Le Jolis and Rosenvinge's opi- 

 nions. Ol' several of the forms recorded by authors as distinct 

 species, I have certainly found thoroughly typical specimens which 

 were easy to determine, but besides these niv material contained a 

 great raany specimens which had characters in common with two 

 or three other species, so that il was quite impossible lo know- 

 how to classify them; and by the occurrence of these intermediatc 

 forms, such an even and continuous series of forms were often re- 

 presented that I could only regard them as varieties or forms of 

 the same species. Ha vin g made these introductory remarks, I shall 

 now proceed to point out in more detail the reasons which I consider 

 most important and on which I have based my definition of species. 



163. E. Linza (L.) .1. Ag. Ulva Linza Lyngb., Hydrophyt., p. 32. 

 A species fairly rich in forms, the thailus heing sometimes 



(pule smooth and sometimes having a strongly crisped or undula- 

 ting surface. Of the forms mentioned by Le Jolis (1. c), I think 

 I have been able to identify more parlicularly f. undulata and f. 

 plana. To unite this characteristic and easily distinguishable spe- 

 cies with other Enteromorpha species, as Le Jolis does, seems to 

 me unjustifiable. 



This species occurs on open sea-shores near low-water mark, 

 especially in rock pools, and in sheltered piaces in shallow water. 

 It grows attached to rocks and stones, sometimes also as an epi- 

 phyte. Fruiting specimens were found in May, June, July, October, 

 November. 



This is a common species of the Færoese coasts where it was first 

 found by Lyngbye (1. c.), who writes: -- »Ad insulas Færoenscs hic 

 illic copiose.« 



164. E. intestinalis (L.) Link. Rosenv. emend., Grønl. Havalg., 

 p. 957. 



var. genuina. Rosenv. 1. c. p. 957. Ulva enteromorpha y, intesti- 

 nalis (L.) Le Jolis, Liste, p. 46. 



The cells in the specimens referred to this variety all have an 

 inner wall somewhat thickened which is thickest in the cells at 

 the base and then often grows thinner almost imperceptibly in those 

 of the upper part of the thailus. I have, however, nol met with 

 an inner wall as thick as that figured by Ahlner (1. c. f. 16). The 

 typical specimens are all branchless and without, or with hardlv 



