60 Mr. W. J. Sollas on two new and 
its body-spicule, and regarded the mucronate spicules as more 
or less peculiar to the diaphragms; but after meeting with 
sponges of other genera, such as Sfe//etta, in the chambers of 
our Cliona, I began to suspect that the sword-like spicules . 
mightbelong to a different species—a supposition which became 
confirmed on finding diaphragms in which the sword-like 
spicules were the chief constituents, to the entire exclusion of 
mucronate ones. ‘This led me to examine each chamber of the 
Cliona-burrows separately by reflected light ; and I then found 
that those chambers which were provided with diaphragms of 
mucronate spicules exhibited the same spicules scattered over 
their walls, and, similarly, that chambers in which ensiform 
spicules were present were closed by dianhragms into the 
composition of which ensiform spicules chiefly entered. The 
spiculation of each chamber was pure; those that contained 
mucronate spicules never contained ensiform ones, and vice 
versd. To make quite sure of this, I then proceeded as fol- 
lows :—Under a magnification of about 50 diameters I picked 
out a cell, the openings to which were guarded by diaphragms 
of one kind or the other, say of mucronate spicules ; the edge 
of this cell was then marked by a fine-pointed pencil for the 
purpose of identification. Next I drew out two pieces of 
glass tubing to very fine capillary terminations, and filled one 
with water and the other with dilute hydrochloric acid ; 
working now under a watchmaker’s glass, I inserted the capil- 
lary end of the tube containing acid into the marked chamber, 
and expelled a drop of the acid into it. By the resulting 
solution of its walls its spicules were detached and set free, so 
that it only remained to introduce the capillary end of the 
other tube into the chamber, and by forcing out the water in 
a fine jet to wash its contents into an excavated glass slide, 
where they could be examined by transmitted light. This 
operation I performed many times, and so convinced myself 
of the complete correspondence between the spicules com- 
posing the diaphragms and those lying on the walls of the 
same chamber. Similarly the fragments of dried sarcode 
present in some of the chambers always contain the same 
kinds of spicule as the associated diaphragms. 
Finally, having made sure that I had present in my speci- 
men of J/si’s two species of Cliona, the chambers of which 
appeared to be inextricably entangled with each other, I was 
able by a little careful searching to trace out the distribution 
of each; and I then found that the chambers of one species 
never opened into the chambers of the other, but that com- 
municating chambers were always occupied by one and the 
same species. This is indicated in Pl. I. fig. 1, where the 
