374 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
APLYSINA INFLATA, Carter. 
Synonymy :— 
1881, Aplysina inflata, Carter (5). 
1889. Aplysina inflata, Lendenfeld (20). 
This curious species is represented in the collection by two fistulee, broken 
off from the rest of the specimen. Lach of them is partially open at one end 
and entirely closed at the other. Presumably the aperture at the one end is 
the spot where the fistula has broken away from the rest of the specimen, and 
this is therefore the lower end. No trace of attachment can be seen on 
either of the fistulee at any part of the surface. 
The height of the fistulae is 45 mm. in one case and 100 mm. in the other ; 
each of them varies in diameter from 15 mm. to 20 mm., but the actual 
sponge-wall does not exceed 1:0 mm. in diameter. 
The surface of the specimen and the structure of the sponge-wall, both in 
skeleton arrangement and xarcode, agrees extremely closely with Carter's 
original description. 
Locality. Sherm Sheikh. 
Distribution. Red Sea, Australia. 
APLYSINA PRATENSA,n. sp. (PI. 36. fig. 11.) 
This new species has been created for the reception of a single specimen of 
a form somewhat similar to that of Aplystna inflata, Carter, but which differs 
from the latter in many important characteristics, and notably in the 
skeleton. 
The specimen (Pl. 36. fig. 11) consists of an irregular spreading mass, 
which is, however, very incomplete. No portion of the basal surface, or of 
the body to which it was attached, is present, and the specimen merely 
consists of a shell of variable thickness, partly surrounding a large central 
cavity ; a considerable portion of the wall of the cavity is missing, however, 
and other gaps occur in the wall. The appearance of these latter apertures, 
which are nearly circular in shape, suggests that possibly digitiform processes 
have been broken away from the specimen. Also in several places low 
prominences and thickenings of the crust occur, which are apparently the 
commencement of further processes. 
The sponge-wall is usually very thin, and in most parts of the sponge does 
not exceed 1-2 mm. in thickness, but where the hillocks and thickenings 
referred to above occur it may be as much as 5 mm. thick. 
The surface of the sponge is covered with conuli, scattered irregularly over 
the sponge. They are frequently connected with other conuli by ridges, 
sometimes a series cf them being united to forma clear upstanding ridge. 
They vary considerably in height, and also in frequency of occurrence, in 
different parts of the specimen. The average height is 2 mm. to 38 mm., and 
they are usually about 5 mm. to 8 mm. apart, though in some cases they are 
