colony could only be inferred, but it seems to have been at least 30 cm., in contrast to the 17 
mentioned in the Challenger Report. Wavy longitudinal lines on the main stems correspond to 
the large internal canals. 
Previously recorded from Zanzibar. 
Genus Pseudocladochonus. 
1. Psetidocladochonus mosaica n. sp. (Plate XV, Figs. 5 and 9; Plate XXVII, Fig. 7). 
Stat. 289. 9 0 o'. 3 S., 126° 24/. 5 E. 112 M. Mud, sand and shells. 1 Ex. 
To this interesting genus we refer a remarkable small specimen, 2.6 cm. high, which 
unfortunately, owing to its brittle nature, was broken. It shows a stem with a maximum diameter of 
2 mm., which divides at the base into two approximately equal broken branches which carry 
two or three secondary branches with polyps. Three anastomoses are seen between two slender 
parallel branches which have a diameter of 0.75 mm. The polyps stand out at an acute angle 
to a height of 1.8 mm. measured along their mid-line. They have a basal diameter (measured at 
right angles to the polyp axis) of 0.55 mm., narrowing to 0.35 mm. at the apex. On the surface 
of the branches and polyps, but not of the basal stem, are seen eight clear longitudinal grooves. 
The entire surface of stem, branches and polyps is covered with a remarkable mosaic of broad 
warty plate-like spicules, oblong in shape, though varying to almost circular, which are firmly 
united together by the interlocking of their irregular dentate margins. The interlocking reminds 
one of the sutures of some skull Tones. Many of these pavement spicules are so thin and flat¬ 
tened that they approach the scale type. 
The mosaic spicules include the following forms : 
( a ) almost oblong, very warty, thick plates, with truncate or rounded ends, and interdigitating 
marginal processes, sometimes frayed. Average dimensions are 0.6 mm. X o. 14 mm.; 
ib) a few triangular forms, with broad bases, tapering to an apex. The average length is 
0.4 mm., with a basal brea'dth of 0.15 mm.-, 
( c ) Shorter forms of the ( a ) type, sometimes approaching squares. Average dimensions are 
0.25 mm. X 0.15 mm.; 
( d ) forms with a median waist, not far from the type figured by Kinoshita (Annot. Zool Japon. VII, 
1909, Plate III, fig. 3). The average length is 0.28 mm., and the greatest diameter 0.17 mm. 
Internal to this outer layer of spicules there lie narrow delicate irregular rods, such as 
are characteristic of some Telestos. More numerous are coarser branched forms more densely 
covered with compound warts. Some of this type are narrow and more flattened, with dentate 
margins. A small amount of a horny substance lies in the internal canal walls between the 
spicules. The longest internal warty rod measured 0.75 mm. So dense is the internal spiculation 
that at first glance the specimen would seem to belong to the Scleraxonia with an axis of fused 
spicules. By closer examination, however, and from sections made from our somewhat scanty 
material, we were convinced of the presence of eight central canals, with which the cavities of 
the polyps communicate, the canal walls being densely filled with spicules. On these grounds we 
must refer the species to the genus Pseudocladochonus, regarding the stem, branches and polyps 
as primary, secondary and tertiary zooids. 
