22 



adhering and provided with reproductive organs, which on a cursory examination might be 

 considered as a new thickening layer of the thallus of the species in question. The specimens 

 in this collection are even more burdened with lower animals than those from the other area 

 mentioned, especially small corals, Bryozoa and numerous worms as wel! as boring algae, 

 penetrating and disturbing the tissue. Thus, an intense struggle for existence is to be seen 

 partly between the algae mutually, partly and especially between plant and animal. There is 

 scarcely a single specimen not being burdened with such objects of one kind or other. Numerous 

 new hypothallic layers are to be found in sections not only of the crustlike part of a specimen, 

 but very often in branching forms too, and as a rule owing to extraneous objects. In other 

 sections is often to be seen a conglomerate of divers calcareous algae (especially Lithothamnia 

 as well as Squamariaceae) and animals, one more or less covering the other, sometimes even 

 forming almost regularly alternating layers. 



It is extremely difncult to clefine such stunted specimens with certainty, in several cases 

 quite impossible. Besides, the very greatest number of specimens apparently belonging to the 

 species in question are sterile, in some cases provided with sporangia, seldom are to be seen 

 a few conceptacles of cystocarps, and not a single one with antheridia. Such specimens scantily 

 fertile have been collected in the months of May, June, July and December. Therefore, it must 

 be the subject of future investigations to show to what extent the forms here mentioned really 

 belong to the species to which the) - are now referred. It may also be noticed that several 

 specimens come near to the following species, L. australe, ancl a sure delimitation can not be 

 founded on the materials present, although, on the other hand, there is no doubt that the 

 said species in fact are specifically distinct. 



The form named f. pteridoides is partly resembling f. crassiuscula in habit, partly a 

 little differing from it (PI. II, fig'. i — 4). The specimens of this form are, however, mostly young 

 and not well developed. The crust is sometimes thicker than in typical specimens of f. crassiuscula, 

 and on the other hand the branches are shorter, but this is owing to extraneous objects being 

 covered up or other species attaching themselves to the crust and being overgrown. The 

 consequence of this is a later and less vigorous development of the branches, such as to be 

 seen in numerous specimens of L. fruticulosum from the Adriatic. As to structure the form 

 in the main agrees with the other forms of the species. So also as regards the conceptacles 

 of sporangia, which, however, are sometimes more confluent than in the other forms. The 

 chief difference which is now to be ascertained is in the conceptacles of cystocarps. 1 have 

 certainly seen but a few ones in young specimens, and — as formerly remarked — even these 

 organs are somewhat varying in this species. The said conceptacles in f. pteridoides are of 

 aboul the same diameter as in f. crassiuscula. Seen from above they are, however, less distinctly 

 defined, lower, with a more acute ancl distinct tip than in the latter form, the conceptacles of 

 which are frequently low conical, though more arched, or approaching a subhemispheric-conical 

 shape, and the tip indistinct and apparently sooner falling away. It may however be observed 

 as mentioned in Lithoth. Adriat. Meer., the conceptacles of cystocarps in f. crassiuscula 

 may sometimes be rather high and almost superficial, sometimes low, but little prominent, and 

 that when emptied they often become overgrown by new-formed tissue. 



