VoL. 2] Robertson.—Non-Incrusting Bryozoa. 237 
monograph upon the British Polyzoa is the most complete and 
exhaustive of any recent work, and its method is generally fol- 
lowed by other workers, it is here adopted as the basis of classi- 
fication, although his conclusions are not always accepted. 
Free use is made of the diagnostic definitions given by that 
author, especially for families and genera, supplementing and 
amending where necessary for greater accuracy, or in order to 
include forms peculiar to the region. Synonymy is based upon 
that of Hineks, further supplemented by Miss Jelly’s invaluable 
Synonymie Catalogue (’&9). No attempt has been made at re- 
vision of the classification. It were useless to undertake such 
a task except after careful study and comparison of all large 
collections. 
It is needless here to enter into an exhaustive discussion of 
the bryozoa as a class. Such can be found in any of the more 
recent treatises on zoology, and the reader desirous of obtaining 
a full, clear, and delightfully written article on the group, is 
referred especially to that by Dr. Sidney F. Harmer (’96). For 
the sake of clearness and convenient reference, however, a few 
definitions of terms used in this paper are given herewith. 
Bryozoa and Polyzoa are synonymous terms. These are 
colonial animals, and the technical term used to designate the 
colony as a whole is zoarium. An illustration of a bryozoan 
colony or zoarium may be found in any of the habit sketches, 
especially the photographs (Pl. XVI). The units of which a 
zoarium is composed consist of the zowcia and their contained 
polypides. A zocecium is a chamber or sac, in which the poly- 
pide, consisting of a digestive canal and a circlet of tentacles, is 
lodged. It may be ealeareous and opaque, or semi-calecareous 
or chitinous and transparent. The contents of a zowcium whose 
walls are transparent are easily made out. Below is given a 
figure of a zocecium of Beania mirabilis with its contained poly- 
pide in a state of retraction folded within it. The zoccium 
(z@.)is seen to be a sae or bag whose front or ventral face is 
bordered with a number of spinous processes, some erect (é. sp.), 
others curved (c. sp.). Within the zoccium is the polypide 
(pd.) consisting of a bent tube, the intestinal canal, having 
