342 Prof. M‘Intosh on Cephalodiscus, a new Type 
instead of forming a mere anterior appendix, it overlaps the ad- 
joining parts to a great extent. In Cephalodiscus it is attached 
to the anterior end of the body, in front of the mouth, by a 
central pedicle, but its broad scale-like margin is quite free 
all round and can readily be raised. Transverse sections 
show that the pedicle of the organ has three main pillars, 
viz. two lateral and onecentral. ‘The outer surface of the late- 
ral is covered by the hypoderm continued from the dorsal 
surface of the disk, and which passes to the basal region of 
the branchiz. Beneath the basement tissue, under the fore- 
going, strong bands of muscular fibres pass along each side of 
the pedicle to radiate into the outer region of the disk. The 
central pillar is composed mainly of what seems to be elastic 
tissue, which is continued upward to a granular glandular 
area, which fills the space between the ovaries. The upper 
region of the latter space is angular, the lower convex and 
rounded, and having the foregoing pillar connected with the 
elastic tissue which bounds the entire area. The central 
region of the latter is filled with granular glandular tissue, 
and probably is an anterior process of the buccal region. 
Whether any space exists on each side of the central pillar 
or lamella is an open question; but in some of the. prepa- 
rations a finely granular substance like coagulated fluid 
occurs. 
Attached to the posterior part of the disk, and apparently 
running from edge to edge so as to become connected with the 
broad apron-like lamella on each side of the mouth, is the 
basal tissue of the plumes, most of which remain fixed to the 
disk on its removal, only one or two clinging externally to the 
margin of the lamella. This basal collar is tinted of a brownish 
hue by transmitted light; and twelve plumes™ arise almost in 
linear series from its dorsal edge, six on the one side of the 
median line and six on the other. ‘The plumes are nearly of 
uniform size, and consist of a central stem, slightly crenate 
posteriorly, and furnished with a series of longitudinal mus- 
cular fibres; while distally it has a peculiar bulbous enlarge- 
ment, which at first sight resembles the tip of certain medu- 
soid tentacles, bristling with dart-cells and pigment. ‘The 
rugose appearance, however, is due to large gland-cells 
containing granules and globules; and the tissue seems to be 
a further development of the somewhat large hypodermic 
granules of the tips of the pinne. The bulbous end of the 
stem shows a rather regular disposition of these cells and 
globules, in transverse section, especially at the circumference ; 
indeed the appearance of such a section recalls that of the 
* Hence the specific name dodecalophus, 
