THE VICT.ORIAN NATURALIST. 19 



where the basalt has been cut through vertically to an old 

 river bed which is about 90 feet below the surface level of the 

 lava flow. The irregular floor of the quarry is about half an acre 

 in extent, and the walls are perpendicular cliff's of roughly 

 columnar basalt. The rain-water drainage of the floor and water 

 which oozes from the surrounding rocky walls forms in pools here 

 and there. One of these pools is at the foot of the vertical wall 

 on the northern side, thus enjoying a maximum of shade, and 

 there, a year ago, the Monostroma was plentiful, associated 

 with Enteromorpha intestinalis, Link, and Zygnema, sp., which I 

 have not found in other than a sterile condition. The Monos- 

 troma appeared when viewed from the top of the quarry wall 

 like a floating collection of large lettuce leaves, having exactly 

 that light green colour and crinkled surface. On closer exami- 

 nation it was seen that many of the plants were floating at the 

 surface, partly buoyed^ up by imprisoned gas which ballooned 

 portions of the thallus, while parts of these and the whole of 

 other individuals were lightly touching the mud at the bottom, 

 being weighed down by a little quarry dust, and, to some extent, 

 by large numbers of a small fresh-water mollusc. If the whole of 

 these plants in the pool had been straightened out in one plane 

 the total area would have considerably exceeded the area of the 

 water surface. The size of this species often exceeds that given 

 in the technical description by a inch or more, but in such cases 

 the thallus is invariably in a torn and dilapidated condition, 

 and all the plants approaching mature size have torn or split 

 margins. 



The shallow, grassy pool from which the new species of 

 (Edogonium was obtained is one of many small depressions of 

 only a few feet in diameter and under a foot in depth, on a gentle 

 northern slope of the Yan Yean drainage area. These small 

 holes are full only during the rainy season, and are then isolated, 

 except for the more or less swampy ground, on which grow 

 various terrestrial and semi-aquatic plants. 



The new species of Desmids were found amongst weeds in a 

 permanent swamp near the rifle range at Cheltenham, a moor- 

 land depression such as many others in the district, and supplied 

 with water by surface drainage and soakage. The weeds of the 

 swamp were chiefly Potamogeton natans and Myriophyllum varii- 

 /olium, intermingled together with terrestrial grasses which had 

 been some time submerged. Pleurotcenium ovaluni, Nordst., 

 var. tumidum, Mask., of which a new zygospore is described, is 

 found also in New Zealand. 



Description of New Forms. 

 Xanthidium gloriosum, G. S. West (sp. n.) 



Very large, almost i^ times longer than broad, very deeply 



