4 Mr. J. L. Drummond on a new Oscillatoria. 



vey Lake, the only one which I had an opportunity of exa- 

 mining, situated about a quarter of a mile from Glaslough, 

 in which I could trace no similar appearance. 



The history now given of the Glaslough Oscillatoria bears 

 a striking resemblance in some points to that of the O. rube- 

 scens of the Lake Morat in Switzerland, as described by De- 

 candolle in the third volume of the Me'moires de la Socie'te de 

 Physique etd'Histoire Naturelle de Geneve, from which I 

 select the following particulars. It is stated in that account 

 that the lake Morat during every spring presents the appear- 

 ance of a reddish scum upon its surface, which the fishermen 

 express by saying that the lake is in flower. But in the spring 

 of 1825 this phenomenon was so very remarkable as to strike 

 with astonishment the inhabitants of its banks, and an article 

 published by Dr. Engelhardt respecting it excited the atten- 

 tion of the Swiss naturalists, especially those of Geneva, In 

 the year stated, the red appearance continued from the month 

 of November till May, and its unusual exuberance was sup- 

 posed to originate from the great mildness of the winter, and 

 the consequent smaller elevation of the water of the lake being 

 favourable to the development of the matter, which was evi- 

 dently organic, and caused the redness. 



During the early hours of the day the lake presented no- 

 thing remarkable, but soon after there appeared long, red, very 

 regular and parallel lines along its borders and at some di- 

 stance from the shore ; the breezes urged this matter into the 

 little creeks, and heaped it up around the reeds. There it co- 

 vered the surface of the lake like a fine reddish scum, forming 

 patches of colours varying from greenish black to a beautiful 

 red ; it was also seen of a yellow, a red, and grey of every 

 shade ; some of them were marbled, and others presented fi- 

 gures much resembling those produced by positive electricity 

 on the electrophorus. During the day this mass exhaled an 

 infectious odour, but during the night all disappeared, to be re- 

 newed on the following day. 



When the lake was agitated by strong winds, the phenome- 

 non disappeared, but again presented itself on the re-establish- 

 ment of a calm. 



Many species of fish, as perch and pike, probably from ha- 



