R. W. H. ROW—REPORT ON THE SPONGES: NON-CALGAREA. 347 
OPHLITASPONGIA (?) ARBUSCULA, n. sp. (PI. 39. fig. 22; Pl. 40. fig. 25 ; 
Text-fig. 22.) 
This species has been created for the reception of two large tree-like 
specimens which were obtained together from a locality not stated. Hach 
specimen consists of a considerable number of long irregular branches, which 
themselves branch irregularly, arising (and presumably growing more or less 
erect) from a small base. In the larger specimen the exact size and 
character of the pediment cannot be ascertained, as a portion of it is broken 
away, but the portion remaining measures 28 mm. by 15 mm. From this 
base four branches arise immediately, and there is no undivided basal portion 
of the sponge save the flat thin and encrusting pediment itself. The 
smaller specimen is even more incomplete than the larger, and in this case 
the pediment is entirely wanting. 
The branches which form the sponge are irregular in shape, but usually 
more or less cylindrical. Numerous prominences and swellings occur on 
them, however, and here and there short processes arise from them which 
are apparently the commencements of new branches. The actual size of the 
branches also varies. The largest reach an extreme length, in the larger 
of the two specimens, of about 500 mm., but their fairly frequent branching, 
and the junctions which occasionally occur between contiguous branches, 
and also the manner in which the branches lie tangled up together, tend to 
diminish very considerably the height of the actual specimen. The branches 
vary in diameter from 5 mm. to 10 mm. 
The outer surface of the sponge is harsh and often gritty, owing to the 
frequent occurrence of an incrustation of foreign bodies upon it. These are 
mostly sand-grains and minute coral fragments, but an encrusting polyzoan 
also grows over the sponge. The actual surface of the sponge is quite 
smooth, being covered by a very delicate dermal membrane, but it is covered 
with slight prominences and low ridges, owing to the pushing up of the 
dermal membrane by skeletal fibres lying just below. However, there are 
no actual projections of either fibre from the surface, but the spicules project 
very slightly and render it minutely hispid. 
Both the specimens are apparently lpostomous, no oscula being distin- 
guishable on either. The pores are very numerous and small, and are 
scattered all over the sponge surface, there being no special pore-areas. 
The colour of the sponge is described by Mr. Crossland as “ brick-red ” 
during life, in spirit it is dark brown-black on the outside and orange- 
brown within ; the spirit in which the sponge has been preserved is coloured 
bright orange-red. 
