R. W. H. ROW—REPORT ON THE SPONGES : NON-CALCARBA. 291: 
All reference to the geographical distribution of these species is deferred 
until the end of the systematic part of the paper, where a full description of 
the distribution of the Red Sea species will be found, with a discussion of the 
relationship of the Red Sea sponge fauna to that of other parts of the world. 
Only the most important references are given in the synonymy lists attached 
to the various species. 
My warmest thanks are due to Professor Dendy for the very kind way in 
which he has placed his knowledge of the Porifera at my disposal during the 
whole of the work, and also for much valued assistance and advice. 
The collection is to be deposited in the British Museum (Natural History 
Department). 
Class NON-CALCAREA. 
Porifera whose skeleton is typically not composed of calcium carbonate. 
Order MY XOSPONGIDA. 
Non-Calearea which are primitively destitute of spicules and horny fibre : 
with simple canal-system and usually large flagellate chambers. 
Family HALISARCID 4. 
HALISARCA DUJARDINII ? 
Synonymy :— 
1842. Halisarca dwjardini, Johnston (17). 
There is a single specimen in the collection which has been tentatively 
identified as this species, though the malpreservation of the material has 
prevented any very certain identification. It consists of a small cushion-like 
mass, about 30 mm. x15 mm., growing on a piece of coral. The surface 
appears lined with shallow grooves, which are the external indications of the 
folding of the choanosome in the sponge. In these grooves doubtless lie 
the inhalant and exhalant apertures, though definite oscula and pores have 
not been made out. Large irregular inhalant or exhalant canals always 
occur immediately beneath these grooves. 
The folding of the choanosome is clearly distinguishable, and chambers of 
about 260 wx 40 u are arranged in a single series around the folds. No 
details of collared cells or canaliculi leading from or to the inhalant or 
exhalant canals could be made out. 
The ectosome is very thin, and apparently not to be distinguished from the 
mesogloea of the chamber layer. 
The colour in spirit is dirty grey. 
Locality. We Shubuk (8.E. corner). 
Distribution. Red Sea, British Coasts, Mediterranean. 
