102 



to strengthen the resisfiiig power of Ihe otherwise slighlly calcilieii stem. Along 

 the middle of tlie frontal surface of each segment we find an exceedingly nar- 

 row membranous frontal area, which even in its distal part is furnished with 

 parietal muscles (figs. Im — In), which Kirkpalrick has also found in B. 

 (Stirparia) Hnddoni. New colonies arise from the stems of the older, taking their 

 origin between two contiguous segments, and the j'oungest, which have a very 

 small number of zoa>cia, possess only a single stem-segment, which in time 

 increases in lenglh and seems to be formed by a constriction of the j)roximal 

 pari of Ihe anceslrnla (figs. 1 c, 1 d, 1 f). After the ancestrula follow two still 

 solilaiy zooecia, after which Ihe first bifurcation commences. The older colonies, 

 with from 3 — 17 joints, have only one solitary zoa'ciuni, which according to the 

 age of the colony sometimes has altogether 2 — 3 spines, and sometimes none at 

 all, while Ihe distal wall, as in Ihe segments is connected with two calcified 

 bands whicli are fused together in Ihe jiroximal part of the zoa^cium into a ring. 

 A larger or smaller number of the older zoo?cia according to their age show 

 a similar Iransformation, and a comparison between the youngest and oldest 

 colonies leaves no doubl about the fad, Ihal the solitary zooecia in Ihe proximal . 

 portion of the colony are in time transformed to segments, while the proximal 

 segment arises from a constriction of the proximal part of the ancestrula. I cannot 

 determine with certainty how the other segments are formed, but as new colonies 

 can arise between two segments, it seems reasonable to suppose, that new seg- 

 ments can also be formed between two older ones, and the fad that the seg- 

 ments may have a very dilTerent length favours this supj)osition. Neveitheless, I 

 have nowhere found Ihem so short that I could consider them as just beginning. 



The radical fibres, which in the older parts of the stems issue in numbers 

 from uniporous rosette-plales in the areas between the two strong, calcified bands, 

 are simple calcified fibres, which partly cover the trunks, partly project freely 

 from these, hi some places they are pear-shaped, swollen in a part of their 

 course and contain a strongly refractive, shining mass, while such swellings at 

 other places project freely and thereby assume a great likeness to the gonothecae 

 in Ihe Hydrozoa. As far as the physiological importance of these swellings is 

 concerned, I would j)ut forward the supposition that they serve for the accumu- 

 lation of reserve materials. Waters' has found (juile similar formations in liu- 

 gnla (Stirpciriri) glabra Hincks. 



The colonies are frequently compound, and Ihe small colonies have the form 

 of stalked caliculate tufts, the branches of which show (5 bifurcations in the 



' 111, p. 20, fig. 1. 



