40 



Tromsø Museums Aarshefter. 14. 1891. 



named species and rather more like L. intermidium as to 

 the shape of the branches, but it is, like most of the other 

 species of Lithothamnion rather variable. It not seldon ap- 

 proaches much to certain froms of L. Ungeri, espeeially such 

 specimens of the latter the hypothalius of which is reduced 

 or quite wanting* Such I have specimens of L. Ungeri col- 

 lected at Tromso which are subspherical and furnished with 

 an opening through which probably an originally included 

 object has fallen out. These specimens are often much rub- 

 bed on the inner side, without any trace of an earlier crust, 

 and showing the interwalls between the branchsystems. In 

 some specimens collected together with L. fornicatum the 

 branches issue from a thin crust in small, more or less remo- 

 ted, short fascieles, sometimes anastomosing even near to the 

 tip, in habit partly reminding of L. Tjngeri, partly of L. 

 fornicatum, I have been uncertain to which species these 

 really are to be referred, as the organs of propagation are 

 unknown in both the named species. A form of L fornica- 

 turn which in some respects approaches certain forms of L. 

 Ungeri, is represented on plate 1 (the lower figure). On the 

 other hand L. fornicatum no w and then resembles in habit 

 more or less certain forms of L. glaciale or L. intermedium, 

 but it is easely distinguished from these on closer examina- 

 tion. Sometimes L. glaciale and L. fornicatum or L. Ungeri 

 germinate on the same object. Thus I met with full-grown 

 specimens, the one half or part of it belong to L. glaciale, 

 the other to L. Ungeri or i. fornicatum was gro wn together, 

 and I also met with a specimen of L. Ungeri and L. forni- 

 catum grown together. 



The only place where the species in question hitherto 

 has been found is Mestervik in the inner part of Malangen 

 (Tromso amt). Here it was local but appeared in great 

 masses together with scattered individuals of L. glaciale, L. 

 intermedmm and L, Ungeri, covering the bottom partly in 



