146 THE ROYAL SOCIETY OF CANADA 



marshy and contains the familiar cat tails and other reeds, and along 

 this section the bottom of the lake close to shore consists of a soft 

 black mud supporting an abundant fauna and flora. Practically all 

 the species of molluscs in the lake with the exception of two or three 

 were found in this locality. Similar bottom conditions obtain down 

 the east side between the outlet and the entrance to the bay and also 

 for a short distance at the southwestern end of the lake. It is of 

 interest to note that within this zone, consisting of water from zero 

 to ten feet in depth, is confined the molluscan fauna of the lake. No 

 living forms were found in deeper water outside this belt. At its 

 edge also the abundant growth of water plants abruptly stops. Fol- 

 lowing along the zone toward the centre of the lake appears a belt 

 of blackish brown mud, slightly more tenacious than the former. 

 This belt is very irregular, being seventy to eighty feet wide in the 

 northern end of the lake, and almost absent at the southern end, as 

 well as in the bay to the east. No living forms of molluscs, but many 

 dead shells, were obtained here. This area of bottom deposits lies 

 in water ten to twenty feet in depth. 



This blackish-brown mud merges into a very unusual sediment 

 in the deeper waters of the lake. My field notes call it a reddish jelly 

 or ooze. This reddish jelly is covered by a thin layer of very soft 

 mud. Close examination of this red jelly shows it to be finely lam- 

 inated in alternating bands of different composition. These include 

 greyish-white laminae alternating with dark reddish bands. This 

 material was not consolidated in the slightest degree, and was rather 

 difficult to photograph (see Plate I, B) because, during the few seconds 

 required for exposure, the material slumped down perceptibly. The 

 laminae are extremely regular and horizontal for the most part and 

 any appearance of irregularity on the plate is due to the difficulties 

 encountered in transporting such ooze-like material to the laboratory. 

 A sharp knife was used to prepare a surface to be photographed, and 

 this tended to draw out the laminae very slightly. As noted, the 

 plate is natural size. 



In addition to different physical characteristics, the red and grey 

 bands are distinct in chemical composition. The grey bands consist 

 largely of calcium carbonate in a finely divided state like marl which 

 completely dissolves, in hydrochloric acid. The red laminae consist 

 almost exclusively of organic material, though traces of calcium car- 

 bonate are present. On being dried, the organic material was found 

 to burn with a large percentage of ash. It should be said that the 

 quantities used in the above determinations were very small, owing 

 to the mechanical difficulties involved in separating out material 



