472 Mr. A. W. Waters on 
In some species, as, for example, C. denticulata, the joints, 
except in the youngest branches, are always black. In no 
species are the joints black when quite young, and in the ~ 
commencement of a branch there is no discontinuity, the 
breaking through of the walls at a joint occurring later on, 
just as in Cellarta and other jointed genera, There are other 
species in which the majority of joints are light, only the 
oldest ones being black or dark, while in a considerable 
number of species there are only light joints, as in C. eburneo-~ 
denticulata and most of the species with few zocecia in an 
internode. In C. ramosa, Harm., from the Mediterranean, 
the joints are usually light, as is the case in specimens from 
Naples and the Gulf of “Taranto ; ; but in some from Capri 
and Genoa the lower joints are dark or black, and in a speci- 
men from Plymouth the lower joints are somewhat darkened. 
The colour of the joint is undoubtedly useful generally, but 
must be taken in conjunction with other characters ; and this. 
may be said of every single character, and with more material 
their value has to be tested. We must not deal with them on 
too hard-and-fast lines, as if there could be no variation, but 
by taking all available we shall see in which group various 
characters occur, and thus relationships will be found. With 
regard to size and measurements, these are of the greatest 
use in examining a fauna of any locality; but we must 
be prepared to find some changes when spread to distant 
localities. 
Crisia serrata, sp.n. (Pl. XVI. figs. 1,2, 7) 
The zoarium is composed of long, stout, straight inter- 
nodes, the branchless ones having ‘an uneven number of 
zocecia (21-23), while none of the internodes have fewer than 
20 zocecia, and one has 25. There is only one branch to each 
internode, occurring usually after the seventh to eighth 
zocecium on that side. The part of the internole above the 
branch is narrower than that below—a character also figured 
by Busk in C. acropora, Busk. The basis rami is “ wedged 
in’’—that is, the basis rami is short and reaches to the 
zocecium below. ‘The base of the branch is about 0°16 mm. 
and the joints are black. 
The zocecial terminations are very short, directed frontally 
and some distance from the edge of the zoarium, the aperture 
being the smallest of any known species (0°04 mm.), although 
the zoarium is the stoutest of any species of Crista. The 
zocecia are not very tar apart longitudinally (only 0:21- 
Q-24 mm.). There is a large projection belind the end of 
