diminish in number and size on the caudal pedicle. Colors — 
Body and head orange, paler below ; a very few irregularly 
scattered black spots on the body ; lips brown ; dorsal, anal and 
caudal tins with the outer half dusky ; pectorals orange at the 
base, pale yellow on the outer margin, with a black median band, 
broader superiorly ; gill-opening black, with an occasional milk- 
white spot ; nasal papillae and tips of the body spines black. 
The species described above belongs to Section ii. B. of 
Dr. Gunthers’ Catalogue, it measures ten and three-fourths inches, 
and was obtained in the Shoalhaven District. 
UN A FRESH WATER ALGA AT WEST MAITLAND 
WATERWORKS. 
By T. W iiit e l eg g e . 
Geological Survey Branch, 
31st July, 1890.^ 
The Acting Curator, Australian Museum. 
Sir, — I have already forwarded to you a sample of 
the minute vegetable organism, which has of late spread with 
such alarming rapidity through the main reservoir and the settling 
tanks at the West Maitland Waterworks. 
The engineer in charge, Mr. Nicholson, informed me that he 
was obliged to keep men constantly employed in removing this 
vegetable growth, as unless kept constantly in check it chokes the 
supply pipes and obstructs the percolation of water through the 
filter beds. The plant appears to me, upon microscopic examina- 
tion, to be a variety of fresh-water Alga, but as 1 am quite 
unable to otter any suggestions as to the best means for its 
eradication, I ventured to forward you the samples of this Alga, 
in the hope perhaps that you might consider the matter of 
sufficient importance to have a thorough investigation made to 
determine (1) the nature of the Alga, and (2) the best specifics 
for checking or entirely preventing its growth. Mr. Nich olson, 
the engineer in charge of the Waterworks at West Maitland, 
would be pleased to furnish any details you may require with 
regard to the occurrence of the Alga. 
The discovery of an efficient remedy for this pest would be a 
great public benefit. 
I have the honor to be, Sir, 
Your Obedient Servant, 
(Signed) T. W. E. David, 
Actg. Geol. Surveyor in charge. 
