ae 
Knowledge of the Spongida. 315 
surface are a few scattered large vents (fig. 4,@). The spicule, 
like that of E. flabelliformis, is a little thinner, but otherwise 
ranks next in beauty to that of Hetyon sparsus, presenting in 
like manner, from its hispid arrangement over the free sur- 
faces, a beautiful object under the microscope by direct light, 
particularly characteristic of the echinonematous order to 
which it belongs. On the surface of this specimen also are 
scattered small isolated parasitic polyps, about 1-24th inch in 
diameter (fig. 4, e). 
Ectyonopsis ramosa, n. gen. et sp. 
(Pl. XIIL. fig. 5, a, 2.) 
Form :—a thick cluster of branches rising from a hard 
contracted peduncular base; branches compressed, dividing 
polychotomously, when, by lateral union, they may produce 
a clathrous lamina, or dividing dichotomously throughout, 
ending in bifid, thin, expanded extremities, or not dividing at 
all, and ending in a simple wedge-shaped or spatulous expan- 
sion, in the present instance 24 inches in its greatest width and 
1-6th inch in thickness. Consistence firm, resilient, becoming 
hard, compact, and rigid towards the base. Colour now (in 
its dried state) sponge-brown. Surface even ; fibre reticulate, 
with groups of echinating spicules springing from the lines of 
reticulation. No appearance of vents. Pores not seen, from 
absence of the dermal sarcode. Internal structure uniformly 
fibro-reticulate ; solid, presenting no appearance of excretory 
canals; fibre echinated with the spicule of the species. Spi- 
cules of two forms, viz. :—1, acerate, cylindrical, slightly 
curved, obtusely ended, spined irregularly throughout, most 
thickly over the ends, which therefore look larger than the 
centre ; about 48 by 4-6000ths inch in its greatest dimensions 
(fig. 5, a) ; 2, acuate, slightly curved, spined irregularly, chiefly 
over the large end, smooth and pointed at the other, about 53 
by 4-6000ths inch in its greatest dimensions (fig. 5,6). Thus 
these two spicules are very much alike, and, on account of 
one end of the former often presenting a diminution in size, 
appear by gradations to run into each other; but while the 
former is chiefly confined to the axis, the pointed form in 
groups chiefly echinates the fibre. Size of specimen 7 inches 
high, 6 inches broad at the top, and 24 inches thick; stem, 
which is rather compressed, 13 inch in its greatest diameter. 
Hab. Marine. 
Loc. S. Australia. 
Obs. This specimen, no doubt also picked off a beach, is 
very much worn in the outside branches, but the central ones 
