LEUCANDRA WALFORDI. 249 
The specimens usually occur single, but in some instances two or three individuals 
are attached together at their bases. They range from 2 mm. to 3°5 mm. in 
height and from °6 mm. to 1 mm. in thickness. The outer surface is slightly 
hispid with obliquely projecting cylindrical or rod-like spicules; the summits are 
obtusely conical or truncate, without distinctive neck or spicular collar. The 
cloacal tube extends to nearly the base of the sponge; it opens by a circular or, 
in the compressed forms, elliptical aperture, from *2 to *5 mm. in width (Pl. XIX, 
fig. 8d). The inner or cloacal surface of the wall is apparently smooth, and, as 
far as can be seen, without a special spicular layer. The walls of the sponge are 
about ‘2 mm. in thickness ; they are composed of cylindrical or fusiform acerates 
or rods and three- or four-rayed spicules of various dimensions, which for the 
most part are indiscriminately intermingled together. 
The greater number of the simple spicules are nearly straight subcylindrical 
rods, with styliform slightly inflected ends; they are usually broken; the longest 
fragments measure ‘43 mm. in length by -005 mm. to ‘01 mm. in thickness. 
Others are straight or slightly curved, fusiform or nearly cylindrical, with acute 
ends. They range from ‘09 to *29 mm. in length, and from ‘0035 mm. to 
‘007 mm. in thickness (Pl. XIX, figs. 8e—87). Some of these simple spicules 
are disposed nearly parallel with or somewhat obliquely to the outer surface, 
from which their distal ends slightly project. Of the three-rayed spicules 
(Pl. XIX, figs. 8 k—8 7) some are regular,—that is, with the rays of equal length ; 
the rays in others appear, however, to be often unequal, but as one or more are 
usually broken it is not easy to determine how far they may have been similar 
originally. The rays are smooth, straight, or rarely with a slight curvature, and 
they gradually taper to an acute point. Sagittate three-rayed forms appear to be 
absent, but a four-rayed sagittate has been noticed (Pl. XIX, fig. 87). The 
spicules vary considerably in size; the rays of a small form are not more than 
‘03 mm. in length by ‘004 mm. in thickness, whilst those of a large spicule 
measure ‘26 mm. in length and ‘01 mm. in thickness near the centre. In the 
four-rayed spicules (Pl. XIX, figs. 87—8 w) the additional apical ray is usually 
shorter than the three facial rays ; in some instances it is more robust, and some- 
what abruptly pointed. In cross-section some of the spicular rays are distinctly 
elliptical. 
Very little of the character of the canal system can be ascertained in the wall 
of this species ; there are here and there minute circular apertures visible on the 
outer surface (Pl. XIX, fig. 8a) which may be apertures of incurrent canals, and 
traces of winding anastomosing canals are exposed in fractured portions of the 
wall, whilst indications of the larger excurrent canals are visible on the inner or 
cloacal surface. 
The sponges occur detached and free in a decayed rusty rock, mingled with 
