R. W. H. ROW——-REPOR'' ON THE SPONGES : CALCAREA. 203 
Family HETEROPID”, Dendy. 
GRANTESSA GLABRA, sp.n. (PI. 19. figs. 5, 6.) 
The specimen (fig. 5) consists of an irregular syconoid individual with a 
slight division into two persons indicated at one end. Hach of these persons 
has a distal osculum, one of them being closed. 
In the aboscular portion of the sponge is a large rent, so that it is impossible 
to say definitely that the sponge is not colonial in form. The specimen 
measures 20 mm. in length and 9 mm. in breadth. 
The canal-system (Pl. 19. fig..6) is typically syconoid, with fairly thick 
dermal and gastral cortices, and is supported by an inarticulate tubar skeleton, 
composed of large, typically sagittal triradiates, and a few oxea (fig. 6). 
Skeleton arrangement. (PI. 19. fig. 6.) 
A. Dermal cortex. 
The spiculation of the dermal cortex consists entirely of triradiates 
(text-fig. 4,6), which are large and vary in shape from regular to slightly 
sagittal, very frequently with the basal ray somewhat longer than the others. 
They are disposed in an irregular layer over the dermal surface, without 
regard to orientation. The rays are all of equal thickness, but some spicules 
are found in which the rays are much thicker than in others. The rays taper 
from base to apex, and are quite straight. 
B. Tubar skeleton. 
(i.) Oxea (Text-fig. 4,d).—The oxea, many of which have the form of the 
stylotes of Monavxonida, are straight and radially placed on the sides of the 
flagellated chambers amid the triradiates of the tubar skeleton with their 
pointed ends dermalwards. They are extremely few in number. <A few oxea 
are also found in which the gastral end cf the spicule is considerably more 
sharply pointed than in the typical example. They are thickest about the 
middle, whence they taper slightly towards the rounded gastral end, and more 
rapidly towards the dermal end. 
(i.) Triradiates (Text-fig. 4,a)—Large sagittal triradiates forming an 
inarticulate tubar skeleton in which, however, many of the triradiates, both 
in the subgastral and subdermal layers, have their paired rays placed consider- 
ably more deeply than have others. The basal ray is by far the longest of the 
rays, being very frequently almost twice as long as the paired rays, which 
are sometimes slightly unequal in length. The basal ray is quite straight. 
The angles between the rays are all equal at first, but the paired rays almost 
immediate curve outwards to form a typical sagittal spicule. 
All the rays taper froin base to apex. 
