334 
ARTHUR DENDY. 
its own narrow inhalant and exhalant canaliculi, and while 
the ground-mass surrounding these flagellated chambers is 
always opaque owing to the presence of small granules, the 
forms like Spongelia and Aplysilla possess no special 
cameral canaliculi, their large, pouch-shaped flagellated 
chambers receiving the water from the subdermal cavities 
directly by means of the pores in their walls, and expelling it 
also immediately, without the help of any intermediate narrow 
canals, into large exhalant cavities, the diameter of these latter 
being usually far larger than that of the exhalant opening of 
the corresponding flagellated chamber; and that in these latter 
instances the parenchyma in the zone of the flagellated 
chambers is devoid of any granules, being lucid and trans- 
parent.” 
Polejaeff further informs us that “the flagellated chambers 
of the representatives of the genera Aplysina and Yerongia 
are small, pear-shaped, or rather hemispherical, each provided 
with one (?) inhalant and one exhalant narrow canaliculus ; 
and again, the surrounding ground-mass is so very rich in 
granules that the outlines of the cellular elements in the 
neighbourhood of the flagellated chambers are scarcely distin- 
guishable. On the other hand, the flagellated chambers of an 
Aplysilla or Ianthella are large and either of regularly 
elongated form (pouch-shaped) or of quite irregular outline; 
no special cameral canaliculi are to be discerned ; the flagel 
lated chambers receive the water from the subdermal cavities 
by means of numerous pores in their walls, and expel it by 
means of a large exhalant aperture; the surrounding groxind- 
mass is clear and transparent. There are, however, amongst 
the horny Sponges forms uniting these two extreme differences 
in every direction.” 
It would appear from my observations that Stelospongus 
flabelliformis is one of these connecting forms, for although 
the inhalant and exhalant canaliculi are only very feebly 
developed, the ground substance, as we shall see later on, is 
densely charged with minute granules. 
Von Lendeufeld (11) has published a good illustration of the 
