216 Mr. J. J. Quelch on Schizoporella Ridleyi, MacG.., 
be distinct from his Porella marsupium, was named by him 
after Mr. Ridley; and as some misconception of the real 
characters of the species exists, I have deemed it advisable, 
after examining the type specimen, to give a more detailed 
description than has been given of a few of its leading features, 
in order to point out its specific distinctness from Schizoporella 
(Escharina) simplex, D’Orbigny, to which species Mr. Hincks 
has recently assigned it (Ann. & Mag. Nat. Hist. January 
1884, p. 51). 
The most striking feature of Schtzoporella Ridleyt is the 
infraoral, bluntly-pointed projection on which the avicularian 
pore is situated. This is not merely a swelling of the 
common wall of the zocecium, for where the projection has 
been broken away a delicate membranous wall still remains 
beneath it in continuity with the zocecial wall. It seems 
rather to be the basal portion of the avicularian cell itself, 
which entirely occupies the large circumscribed area below 
the mouth of the cell, as originally pointed out by Mr. 
Ridley. 
A clearer idea of this projection will be formed by viewing 
it from the side, so that 1t may be seen in profile, as it would 
be if a median longitudinal section of it were made. It will 
then be seen to arise, at its inferior part, somewhat above the 
middle of the zocecium, as a slightly convex line forming an 
angle of at least 45° with the surface-wall of the zocecium, 
continuing outwards and forwards until it is joined by a line 
drawn from the sinus in the lower lip of the mouth at right 
angles to the zocecial wall. The length of this perpendicular 
line gives the height of the projection above the zocecium ; 
and this corresponds very nearly with the length of the cell- 
mouth, except in the youngest zocecia at the edges of the 
colony, where the projection is smaller, but still quite distinet 
and prominent. ‘This raised portion, seen from the front, is 
nearly semicircular in outline, the curved portion terminating 
at the lateral angles of the mouth, while the straight, flat, 
superior portion forms a platform, so to speak, immediately 
below the mouth. At the outermost pointed limit of this 
platform is the avicularian opening, which can only be dis- 
tinctly seen by looking down from the top of the zocecium, as 
it were. 
The lower lip of the aperture of the zocecium in this species 
is straight, with a shallow median rectangular sinus; there is 
no sinus in the edge of the infraoral projection, that shown 
apparently in such a position in figures of the species being 
really in the lower lip of the aperture of the cell, supposed to 
be seen above the projection; the surface is glistening and 
