VINE : CLASSIFICATION OF THE PALAEOZOIC FOLYZOA. 
41 
integument, whereas the Zooids in the latter are united by an organic 
connecting medium or caenosarc." Mr. Hincks describes the " Ros- 
ettenplate" of Reichert as a "diaphragm, pierced by one or more 
minute orifices, occurring in the walls of the adjacent cells amongst 
the Clieilostomata ... by means of which, communication is 
maintained between all the cells of a colony. ..." I have 
already quoted a passage from Mr. Waters' paper on the Cycloitomata, 
in which the following remark may be found, but I give it again in 
connectioQ with the above. In Heteropora j^elUcidata, Waters, there 
is a plate or diaphragm " seemingly perforated in the centre, it occurs 
in the middle of the pore-tube, and thus it seems entirely to corres- 
pond to the simplest rosette-plates of the Cheilostomata."* Mr. Busk 
observed The Polyzoa are always associated into compound growths, 
made up of a congeries of individuals, which though distinct, yet 
retain some degree of inter-communication." From all this we glean 
the fact that in recent species of Polyzoa, a means of inter-commu- 
nication do exist between cell and cell, both in the Cyclostomata and 
the Cheilostomata, and inferentially we may conclude that such 
means might have existed in the cells of true fossil forms of Polyzoa 
as well. 
As regards the affinities of the Polyzoa, much diversity of 
opinion exists. In his work on Pala^ontologyj Professor Owen says 
" The Bryozoa are allied to the compound Ascidia, but not one of 
the Ascidian MoUuscoids quit the ovum as a gemmule swimming by 
means of ciha, and no Bryozoon quits the ovum in the guise of a 
cercarian or tadpole, to swim abroad by the alternate inflexions of a 
caudal appendage .... The Bryozoa, whether regarded as the 
highest organised Polypes, or as the lowest organised mollusca, or as 
an intermediate type, are treated of in systematic Palaeontology in 
the position here assigned to them . The practical Palaeontologist 
finds himself compelled to arrange and study the Bryozoa along with 
the corals, if only on account of the difficulty he, in many cases, 
experiences of determining which class of Polypi his specimens belong- 
to," Mr. Hincks condenses the opinions of several naturalists in a 
* Qaarfc. Jour. GeoL Soc, Vol. 40, p. 677. 
t Edition 1860, p. 27, &c. 
