348 Prof. M‘Intosh on Cephalodiscus. 
projects beyond the margin of the disk. The tentacular 
plumes soon exhibit a symmetrical series of filaments on each 
side, the general outline of each process being still abbreviated 
and rounded. Shortly atter this stage the bud separates from 
the parent (the plumes being still small). The pedicle is 
fairly developed; and as soon as it is detached (and some- 
times before) a little bud appears near the tip. The peduncu- 
lated bud in Rhabdopleura somewhat resembles this form, 
though the tentacular plumes greatly diverge. 
Cephalodiscus thus differs from Rhabdopleura in regard to 
the ccencecium, in the much greater size of the buccal shield, 
in the remarkable branchial or tentacular plumes, in the struc- 
ture of the pedicle, and in the perfectly free condition of the 
polypides. 
Cephalodiscus and Rhabdopleura agree in the absence of the 
calyciform membrane connecting the bases of the tentacles, 
in the position of the mouth, which opens ventrally behind 
the buccal shield, in the general structure of the alimentary 
canal, and in the position of the anus. The development of 
the young buds issimilar. Both connect the ordinary Polyzoa 
with Phoronits. 
Cephalodiscus naturally falls under Prof. Allman’s section 
Polyzoa Aspidophora, and further demonstrates the correctness 
of that author’s opinion in regard to the systematic position of 
these anomalous forms. Prof. Lankester’s designation 
“¢ Pterobranchia,” as applied to Rhabdopleura, is less suitable 
than the foregoing. 
CEPHALODISCUS, n. g. 
Coencecium consisting of a massive, irregularly-branched, 
fucoid secretion resembling chitine, hispid with long spines 
of the same tissue, and honeycombed throughout by irregular 
apertures, channels, and spaces, in which the separate and 
independent polypides occur singly or in groups. 
Lophophore richly plumose, with an enormous buccal shield 
and large oral lamella, the mouth opening between the two. 
Anus on the anterior dorsal prominence, behind the plumes. 
Two large eyes abutting on the ovaries. The homologue of 
the funiculus is short and quite free, its tip serving for the 
development of buds. 
