190 e 
purpose much of the material entrusted to me, especially as 
in the other cases cited above I had found males and females 
in different cavities, not merely of the same colony, but of the 
same branch of the colony. 
Summary.—The principal features of the new species now 
under consideration may be briefly stated as follows :— 
Cephalodiscus (Idiothecia) gilchristi, n. sp. Material, from 
the Cape Seas at depths of 30 fathoms or more. Tubarium 
irregularly branched, some of the branches connected by solid 
cross bars; distance from one branch to the next 30 mm. on 
an average, extremes 55mm. and1z7mm. Width of terminal 
branches, not including spines, about 5 mm., width of basal 
stems about 10mm. Ostia numerous, except in the main 
stems and attached base. The tubular cavities of the tubar- 
ium do not communicate with one another, and each is occu- 
pied by a single polypide and its buds, of which there may be 
from 2 to5. Tubes 4 or 5 mm. long, 1 to 1.2 mm. across ; each 
tube with a single ostium, oval, 1 by 1.2 mm. across, sessile, 
or in the terminal branches with short, rarely long, peristomial 
tube. Spine-like processes of tubarium long and slender ; 
many of them can be traced for a considerable distance into 
the tubarium, each spine accompanying one of the tubes, 
more or less. Length of freely-projecting portion of the spine 
about Io mm., width 3 to‘4mm. Occasionally an ostium has 
no spine directly related to it, or it has more spines than one. 
Polypides not black, but there is a broad dark margin to the 
buccal shield, not continued on to the posterior lobe. Dis- 
tance from end of visceral mass to end of plumes about 1°8 
mm.; ditto to front of buccal shield about 1-5 mm. ; ditto to 
anus about 1mm. Plumes six pairs; tips of the plume-axes 
small, not globular, without clear, refractive beads. Stomach 
dilated ; anal aperture large. Stolon longer than the body. 
Polypides male and female ; alike except as regards the gonads, 
and may occur in different tubes of the same branch of the 
colony. Free ova found in the cavities of the tubarium mea- 
sure from *4 by °33 mm. to °5 by ‘4 mm. 
Short diagnoses of Cephalodiscus sibogae, gracilis, hodgsoni, 
dodecalophus, nigrescens and levinseni, similar to the above 
summary of characters of Cephalodiscus gilchristi, are given 
in my report on Cephalodiscus in the ‘‘ Discovery ” Expedition 
Reports, 1906, pp. 7-11. 
The seven species of Cephalodiscus, of which descriptions 
have up to the present been published, may be quickly dis- 
tinguished by the characters set out in the following table. 
