336 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
In addition to these large forms there occur also larger numbers of smaller 
anisochelee, which are also scattered about without orientation or arrange- 
ment. They are apparently the young forms of the above anisochele, as all 
intermediate stages can be found. 
Gi.) Sigmata. (Text-fig. 16, B.) 
The sigmata are comparatively large and of typical C or S-shape. They 
are not nearly so numerous as the anisochele, but, like them, they are not 
on 
E 
Fig. 16.—Esperella euplectellioides. Microscleres, x 675. 
orientated at all in the sponge. They measure on the average 0°05 mm. to 
0:06 mm. across the curve, and about 0°1 mm. along the spicule itself. They 
are comparatively slender, being not more than 00012 mm. in diameter. No 
small or immature sigmata were seen. 
Locality. No locality is given. 
Distribution. Red Sea. 
HISPERELLA FISTULIFERA, n. sp. (Text-fig. 17.) 
The characteristic feature of the present species is the external form. It 
consists of an undivided basal portion, of considerable size and very irregular 
shape, from the surface of which arise large numbers of small tubular 
processes, each with an osculum at the summit. These processes frequently 
occur in groups arising from a common stalk, so that the whole group may 
possibly arise by the branching of a single process. They occur over the 
whole of the upper surface of the sponge, and also in considerable numbers 
on its sides. They invariably stand erect, those arising on the sides of the 
mass being sharply curved at their base so as to assume the vertical position 
immediately. 
These processes vary very considerably in length, but never appear to 
exceed J0 mm. when single, but a group of processes as a whole may reach a 
