354 P Kramp. 



or better manner; it is fortunate that tlie subdivisions nevertheless 

 appear natural and reasonable. Further, it is almost the same clas- 

 sification as G. O. Sars has used in "Bidrag til Kundskaben om Norges 

 Hydroider" 1873 (48). 



I shall not enter upon a detailed discussion of the influence of 

 the bottom on the distribution of the species. The little the avail- 

 able material shows in this regard will appear from the tables. If 

 we count up the species which occur on the different kinds of bot- 

 tom, we get the following numbers: 



No. of species 



Only on bottom with vegetation 17 ^ ,^^ , ^^ 



-^ . , 1 . , I 28 on bottom 



Common for bottom with and without (with ve"etation 



vegetation 1 1 { , ,. . , . 



^ I 16 on bottom 



Only on bottom without vegetation 5/ without vegetation 



Total . , '. 33 



Stolonisation 



Plate XX and Plate XXI, figs. 1, 2. 



It has long been known, that ends of erect branches can grow 

 out in filiform, stolon-like formations and fasten themselves on for- 

 eign objects, but not very much has been written about this, only 

 scattered remarks occur here and there. 



Occasionally systematic importance has been given the stolonized 

 branches. B. von Campexhausen 189() (18) p. 306, justly calls at- 

 tention to the error in this: "Unter den Hydroiden von Ternate 

 zeigen die verschiedensten Genera und Familien Rankenbildung". 



Thompson 1884 (55) figures "tendrils" of Sertnlaria albimaris and 

 Sertiilarella riigosa. "How they end and whether they serve for at- 

 tachment, I do not know" (1. с p. 5, PI. I, figs. 1, 10, 13). 



Hartlaub 1901 (24), pp. 19, 34 — 37, 50, mentions some examples 

 in species of Sertiilarella, and expresses the desirability of having at 

 some time a comparative account of these phenomena. Such an 

 account cannot be given here; I only wish to note the examples of 

 stolonisation which I have observed in the material from the Dan- 

 mark Expedition. 



Billard 1901 (10) communicates some observations on stoloni- 

 sation in different species, mostly in aquaria. Billard has made 

 such stolons attach themselves to glass plates and he has found 

 that they show a very considerable rapidity of growth. About the 

 occurrence of stolonisation in nature it is only said: "- - - les 



