442 DR. S. F. IIARMEU ON THK 



of this argument lias not escaped the notice of some other 

 Avriters. 



The first specimens examined were received from a waterworks 

 system (No. 4, above), which does not permit itself to be men- 

 tioned by name, at the end of October 1912. They were remai-k- 

 able for the extraordinary freedom with which hibernacula were 

 developed. In correlation with the lateness of the season, the 

 polypides ha.d degenerated, and the zocecia were represented 

 merely by their empty ectocyst. Nearly every zooecium, through- 

 out the whole of the material, bears one or two hibei'nacula in 

 the place of the ordinary lateral daughter-zocecia ; and, if it 

 happens to be at the end of a branch, a terminal hibernaculum 

 as well. These hibernacula (PI. LXII. figs. 1-10) are, almost 

 without exception, of an elongated fusiform shape, although 

 varying much in length and, to a less extent, in breadth. They 

 thus differ strikingly from most of the figures of these structures 

 which have previously been published. 



The hibernacula were originally described, under the name of 

 " hybernacles," by Dumortier and Yan Beneden, in the memoir 

 cited above (p. 51, pi. i. fig. 1"; pi. ii. figs. 24-35). Although 

 shown as replacing lateral bvids, and therefore in the same 

 position as in the specimens which have come under my notice, 

 they are described and figured as short bodies, not more than 

 about one-fifth of the length of the zocecia. They are pointed at 

 their free end, and were said to be always strongly compressed. 

 In colour they were greyish black. 



Kraepelin, who states (87, p. 76) that the hibernacula do not 

 appeal- to have been found by any observer since Van Beneden, 

 describes and figui'es them (pi. iv. fig. 117) as swollen and ellip- 

 soid or irregular, and states that they are j^ellowish in colour, 

 and that they have a considerable amount of calcareous matter 

 in their cuticle. Several of the specimens figured by Kraepelin 

 resemble the hibernacula described by Van Beneden in their 

 form, but one or two of them are fusiform, although riot so elon- 

 gated as most of the hibernacula which have come under my own 

 observation. Some of them remain attached to the substratum 

 when the zooecia, which have meanwhile lost their contents, dis- 

 integrate and break up. In the second part of his monograph 

 (92, p. 61) Kraepelin refers to the irregular form generally 

 possessed by the hibernacula. He describes the occurrence in 

 them of an elongated polypide-bud (pi. y. fig. 163), which is 

 formed early in their development, in readiness for germination 

 in the ensuing spxing ; and he mentions the yolk-like material 

 b)'^ which the polypide-bud is surrounded. He was unable to 

 discover the mode of formation of the hibernacula. 



Levinsen (94, p. 85, pi. viii. figs 24-26) gives figures of the 

 hibei'nacula Avhich are much like those of Kraepelin. 



Wesenberg-Lund (96, pp. 321, 363, xxiv: pi. iv, figs. 44, 45) 

 found the hibernacula in large numbers in October. They were 

 all of the same fonn and colour as in Kraepelin's description, 



