46 MR. A. W. WATERS ON 
adequate descriptions of the zocecia or of the minute characters. 
The name is accepted, and. subsequently more detailed description 
has been given, though there is the possibility of this only 
relating to a similar form. We have an example in Céllepora 
incrassata of Lamarck, the name being first given to a Mediter- 
ranean species: but under this name Smitt described more 
thoroughly a northern form, which has been thus generally 
known, while a Mediterranean one has been described under 
another name. In such a case it seems better to consider this 
as the species of Smitt, who more fully described it; and to 
replace the present recognized name by another would only 
add confusion, and this is often the result of too pedantically 
endeavouring to follow rules. 
In many cases, purposely, only one or two references are 
given, even where the name has been employed by various 
authors ; but, as far as possible, only descriptions about which 
there was a reasonable certainty have been referred to, leaving 
out probabilities. 
Since Smitt published his papers, the details of the structure 
of the zocecia have been more carefully examined, and it has been 
necessary to give attention to many points which are now 
recognized as furnishing specific characters, for it is known that 
the general appearance is subject to great variation. The use of 
the opercula and mandibles in determining species, which I 
introduced in 1878 *, has been most valuable, and these characters 
are receiving increasing attention. The ovicells are more carefully 
examined than they were at the time Smitt began his work. The 
position and form of the rosette-plates should always be examined 
when circumstances permit; as also whether the connection is 
direct from zocecium to zocecium, or through a pore-chamber 7. 
The position of the rooting process is another character of 
considerable value. In the Cyclostomata the position and 
nature of the “ closures’’ are characters which should not be 
overlooked. The glands at the side of the oral aperture and in 
the avicularian chamber differ considerably in position and size 
according to the species, and there are many species which I 
should recognize from sections of the soft parts; and no doubt, as 
* «The Use of the Opercula in the Determination of the Cheilostomous 
Bryozoa,” Proc. Manch. Lit. & Phil. Soc. 1878, vol. xviii. p. 8, pl. i. 
+ See Waters, ‘ Observations on Membraniporidx,” Linn, Soc. Journ., Zool. 
vol, xxvi. p. 654. 
