POLYZOA OF WATEKWORKS. 447 



who based his conclusions on the general simiUirity of the hibei-- 

 iincula to statoblasts, particuliU'ly those of Fredericella in wliicli 

 no annulus is present. He did not, however, bring forwaid ;iny 

 evidence to show how the hibernacula are developed. Braem 

 (90, p. 112) has disputed Kraepelin's conclusions, basing his 

 objection largely on the assumption that the hibernacula are 

 complete, specially modified, tei'minal individuals of the colony. 

 On this assumption there would be a considerable difference 

 between them and the statoblasts, which are essentially buds 

 produced internally within the body-cavity of a zooecium. 

 Braem's objection loses some of its force if his assumptioir as to 

 their mode of origin can be shown to be incorrect. I think that 

 the evidence here brought foi'ward is sufficient to render the 

 conclusion that the hibernaculum is typically an end-bud of the 

 colony very doubtful. Although the proximal part of its ecto- 

 cyst is commonly a modification of the corresponding part of the 

 ectocyst of the parent-zocecium, cases like those shown in figs. 2 

 and lO appear to prove that the hibernaculum may be formed as 

 an internal bud-like structure, with a complete cuticle of its 

 own ; and there is indeed no very essential difference between 

 the proximal hibernaculum shown in fig. 10 and the statoblast 

 of a Fredericella. I do not, of course, overlook the fact that the 

 statoblasts of Phylactoleemata are developed in a peculiar way 

 from the funiculus of a polypide. But FcdiKlicella is, in any case, 

 only distantly related to the Phylactolpemata ; and the difference 

 between the winter -buds of the two forms is not, apparently, so 

 great as has hitherto been assumed by most observers who have 

 considered the question. 



When one considers the facility with which freshwater 

 organisms, from Protozoa upwards, develop some special cyst- 

 like coat which enables them to survive the winter or periods of 

 drought, one must no doubt be cautious in assuming that the 

 homology suggested is a probable one. But my observations 

 seem to show that the hibernaculum of Pahulicella, like the 

 statoblasts of Phylactolpemata, is a special form of winter-bud 

 which is developed inside the pai-ent zooecium out of a mass of 

 liviug tissue which becomes surrounded by a chitinous coat ; and 

 that thus the two kinds of winter-buds are morphologically com- 

 parable. In view of this consideration it does not appear to me 

 impossible that the hibernaculum and the statoblast represent 

 two different conditions which have been evolved from a common 

 starting-point. 



Tho specimens of this species received from Aberdeen (jSTo. 5, 

 above) agree closely with those just described. Numerous hiber- 

 nacula of an elongated type are present, although they are 

 perhaps more variable in length than in the other sample. 

 Some of them are even longer than the longest described above. 



Faludicella articulata has previously been recorded as an 

 inhabitant of the pipes of waterworks, both at Hamburg 

 (Kraepelin, 85, p. 6) and at Ptotterdam (De Yries, 90, p. 25). 



