XXXVl 
INTKODtJCTIOX. 
The taxonomic value amongst Bryozoa of the arrangement of the 
zooecia in masses of parallel, crowded tubes has been often 
discussed. The distinction was accepted as of generic value by 
Lamarck in 1816, when he separated Alcyonella from Flumatella\ 
for the former genus, as illustrated by the excellent figure of 
Alcyonella fungosa (Pall.) by Allman,^ is characterized by its 
zoarium consisting of crowded polygonal tubes, which rise 
vertically from a series of creeping horizontal tubes. Its structure 
is that of the Eectangulata. 
Zoologists who attached little value to the characters of the 
zoarium early maintained that Alcyonella was only an individual 
variation of Plumatella^ a view that has been urged by Raspail 
(1828), Ehrenberg (1831), and Siebold (1848). Raspail ^ defended 
this view in the famous memoir “Histoire liaturelle de I’Alcyonelle 
fluviatile,” wherein he urged that all the fi’esh-water Bryozoa then 
known were varieties of one species. The validity of the two 
genera was upheld by Allman (1848), as the two forms maintain 
their distinctions even when growing together under precisely the 
same conditions, as the differences between them are always 
constant, and as their geographical distribution is different, 
Plumatella^ for example, being abundant in Ireland, where 
Alcyonella has not been found. Dr. Harmer,^ however, following 
Kraepelin, has abandoned Alcyonella and speaks of Alcyonelloid 
forms of Plumatella, and he remarks^ that the occasional lax 
growth of an Alcyonella causes it to resemble Plumatella, 
. Whatever conclusion may be accepted as to the value of these 
two genera, they illustrate the fact that closely allied forms may 
have strikingly different modes of growth, and show that the 
tendency of the zooecia to arrange themselves in crowded vertical 
series is not of great systematic value throughout the whole group 
of Bryozoa. 
The differences between the proximal and distal ends of the 
zooecia, combined with their parallel growth into massive zoaria. 
^ G. J. Allman. “ A Monograph of the Fresh Water Polyzoa” : Bay Soc. 
1856, pi. iii. fig. 4. 
2 Easpail. Mem. Soc. Hist. Rat. Paris, 1828, vol. iv. pp. 75-165. 
® S. F. Harmer. Polyzoa : Cambridge Ratural History, 1896, p. 494. 
^ Op. cit. p. 505. 
