Hexactinellid Sponge from South Africa. 459 
2. Oxyhexasters, 90-100 w in diameter, with usually bi- 
furcate, but occasionally single, roughened rays. 
Of the two specimens, the smaller, which is almost globular, 
has only a slightly developed root-tuft ; the larger has several 
long digitate processes about 9 centim. long by 1 centim. 
thick, provided with tufts of long pentact basalia, forming a 
dense root-tuft. The total length of the large specimen is 
23 centim., the breadth at the base 18 centim., length of 
body 13 centim., of root-tuft 10 centim. ; diameter of orifice 
7X6 centim.; depth of gastral cavity about 6 centim. It 
should be remarked that the specimens have probably been 
considerably distorted by compression, as the outer veil is 
only intact over a small area of the smaller specimen. 
The dimensions of the smaller specimen are:—Length 
13 centim., with three digitate processes 2°5 centim. in length ; 
breadth 13 centim.; orifice 4centim. ; depth of gastral cavity 
about 4 centim. 
Diact basalia are apparently absent, though very numerous 
long spicules occur which are broken at the end. All the 
young complete spicules are pentactine, and [ have been 
unable to find among them any diacts. In addition to the 
shape of the sponge and the fissile character of the principal 
rays of the discoctasters, the occurrence of spined diacts in the 
gastral membrane characterizes the new species; in all of 
the eight previously described species, [8] p. 105, of this 
genus the autogastralia are hexactine or hexactine and pent- 
actine. In a species of a closely allied genus, Staurocalyptus 
pleorhaphides, Ijima, [4] p. 58, both the dermal and gastral 
membranes are supported by spinous diactines. 
Locality. Large specimen, 73 miles north and 28 miles east 
of Lion’s Head, 140 fath., Cape Colony: small specimen, 
63 miles north and 34 miles east of Lion’s Head, 154 fath. 
Both specimens obtained by shrimp-trawl. 
(1] Scuvuuze, F. E. “Revision des Systems der Asconematiden und 
Rosselliden,” Sitzungsb. Akad. Wiss. Berlin, 1897. 
[2} ‘Challenver’ Hexactinellida, 1887, p. 155. 
[8] ——. ‘Amerikanische Hexactinelliden nach dem Materiale der 
Albatross-Expedition,’ 1899. 
[4] Isrma, I. “ Revision of Hexactinellids with Discoctasters, with 
Descriptions of Five new Species,” Annotationes zoologicw 
Japonenses, 1897, vol. i. 
EXPLANATION OF PLATE VIII. 
Fig. 1. Rhabdocalyptus lophodigitatus, sp. 0., large specimen, reduced to 
one third natural size. The figure has been slightly idealized, 
in order to show the gastral orifice, the basal digitate processes, 
