HEXACTINELLIDA. 21 
without hypodermal pentactins. Awulochone, which has an everted gastral surface, 
differs from the new genus in being stalked, and in possessing only one kind of 
discohexaster.* 
ANAULOSOMA SCHULZII. 
(Plate IIL, figs. 5, 6, and Plate V., fig. 2 a—m). 
Sponge shaped somewhat like a molar tooth, with rounded or carinated mamuillee 
at the lower end, and with a free gastral surface at the upper end. Surface smooth, 
without pleuralia, with a few diactin marginalia at the junction of the dermal and 
gastral surfaces. With a few very small tufts of diactin basalia extending downwards 
from the mammille. Principalia, bundles of diactins, also hexactins, pentactins, 
stauractins, and tauactins. Autodermalia, pentactins ; hypodermalia diactins in bundles 
forming a network. Autogastralia, pentactins, with a few hexactins. 
There are two specimens (A, C) and two fragments (B, D) of this sponge. 
Specimen A (III, 5), the type, from McMurdo Bay, is 6°5 cm. in height, 4°5 em. in 
width, and 3°3 cm. in thickness. The texture of the sponge is loose. The thin felt-like 
gastral surface, with several thin-edged exhalant orifices, is easily distinguishable from 
the lace-like dermal surface, the two being separated by a sharp edge. The oval gastral 
surface, 5 x 3 .cm., which occupies the whole upper end of the sponge, slopes down- 
ce 
wards a little; the largest of the “oscules” is oval, and 1 x *5 cm. in diameter ; 
the walls of the large canal into which it leads are lined simply with scattered 
canalaria in the form of oxyhexasters. The autogastralia are pentactins, and rarely 
hexactins. Two or three deeply curved diactins are present on or near the gastral 
margin, but it is doubtful whether they are really marginalia, or, indeed, whether they 
belong to the specimen at all. The lower end of the sponge is prolonged into two 
rounded extensions, each with a small tuft of basalia. 
The small specimen C (III. 6) is somewhat wedge-shaped, the inferior end 
narrowing to a ridge, with a small tuft of basalia projecting obliquely downwards and 
outwards from only one of the ends of the ridge. The upper end, or gastral surface, 
1:1 em. in diameter, is in the form of a small circular area, with one small circular 
orifice (1°5 mm. in diameter) of an exhalant canal. Round the margin is a cirele of 
small diactin marginalia projecting about 6 mm. The two fragments (B, D) are the 
lower halves of broken specimens ; in them the broken surface shows the openings of 
numerous canals passing vertically upwards from the base. 
In Anaulosoma schulzii there is a marked difference in the appearance of the 
dermal and gastral surfaces, the former showing a fine lace-like reticulum perceptible to 
the naked eye, while the latter has an opaque, felt-like appearance. This difference is 
chiefly due to the arrangement of the hypodermal skeleton. In the dermal region 
* T have recently found microdiscohexasters in Aulochone (Crateromorpha) lankestert Kirkp. from South 
Africa. These spicules escaped my notice when I first described the sponge (Ann. Mag. N.H. (7) VII., 1901, 
p. 457). 
» 
i Ree 
