SPECIES OF CEPHALODISOUS. ‘d 
may be but short, thick lips to the peristomial tube. Most important of all, however, 
is the isolation of the polypides of certain species in tubular spaces in the tubarium, 
in contrast with the occurrence of all the polypides of the colony in one continuous 
cavity in other species. 
Harmer, on p. 6 of his monograph (10), gives a list of the generic characters of 
Cephalodiscus; but while attaching the name of M’Intosh as the author of the 
genus to the name Cephalodiscus at the head of the paragraph, he alters the diagnosis 
of that author by describing the tubarium as “with a continuous cavity or with 
a separate cavity for each zooid.” Until the discovery of C. levinsent it was not 
known that any forms of Cephalodiscus existed in which the polypides had separate 
tubes. The presence of (an average of) fourteen plumes in the polypides of 
C. nigrescens, and the discovery that in both C. nigrescens and C. hodgsoni 
hermaphrodite individuals occur, necessitate further alterations in the diagnosis 
given by Harmer (10, p. 6). 
The isolation of the polypides in separate tubes within the common test is 
clearly a feature of great systematic importance, and for the inclusion of species of 
Cephalodiseus in which the polypides are so isolated Professor Ray Lankester has 
been good enough to suggest the sub-generic name Jdiothecia*. So far as our 
present knowledge goes there are three such species, viz., C. levinseni (text-fig. 3), 
C. nigrescens (plate 1), and an undescribed species obtained by Dr. Gilchrist in the 
Cape Seas. The remaining species of Cephalodiscus, in which the polypides are 
more social and live together in the same edifice, namely, the type species C. 
dodecalophus (text-fig. 4), and the recently discovered species C. gracilis (text-fig. 5), 
C. sibogae (text-fig. 2), and C. hodgsoni (fig. 1, plate 2), are included in the sub-genus 
for which Professor Lankester proposes the name Demiotheciat. Dr. Andersson’s 
note (1) is not sufficiently detailed to enable one to judge whether the Falkland 
Islands specimens belong to C. dodecalophus, as that author suggests, or not. 
REVIEW OF THE SIX SPECIES OF CEPHALODISCUS. 
Genus Cephalodiscus. Polypides secreting a tubarium of gelatinous appearance, 
formed of superimposed lamellae, and with ostia upon the surface. Polypides with 
buccal shield, collar, and trunk. Shield with pedicle arisg from middle of upper 
surface, hollow, the cavity opening typically [ by two small pores (proboscis pores) 
on the dorsal surface. Collar with special paired division of coelom, opening to 
exterior on each side by a canal (collar canal) near the gill-slit; collar produced 
* From idvos, one’s own, personal, private, and @nxn, a case, box, vault. 
{ From dyjptos, belonging to the commonwealth, and 6x7, a case, box, vault. 
t Proboscis pores, gill-slits, and post-oral lamella have not been recognised in the reduced males of 
C. sibogae (10, p. 6), but the neuter individuals of that species conform with the generic diagnosis in these 
respects. 
