DISTRIBUTION OF THE ROTIFERA. 4G7 



Murray has quite lately brought back evidence of a considerable 

 Rotatorian fauna, mostly Bdelloids, which he found living in 

 large patches at the bottom and also on the surface of shallow 

 lakes formed during the short summer period ; most of these are 

 common forms in Europe, Africa, India, and elsewhere, but a 

 few will be described as new species. During the cold weather 

 these Bdelloids contract into little balls and are frozen solid, 

 but revive immediately the ice melts. Amongst the other species 

 Hydatina senta was found in abundance in one of the lakes on 

 Ross Island. 



The very erratic appearance of rare or uncommon species 

 in widely separated places seems to show that distance is no 

 •obstacle to their distribution, provided only that they find 

 suitable conditions. A few examples of such erratic distribution 

 may here be cited : 



Trochosphaera aequatorialis was found by Semper in ditches 

 which intersect ricelields in the Philippine Islands in 1859; its 

 next appearance was in 1889 in Australia, where Gunson Thorpe 

 found this same spherical Rotifer in a pond of the Botanic 

 •Gardens in Brisbane ; a year ago it was once more found by 

 Mr. Colledge near the same locality. 



Trochosphaera solstitialis was first discovered in 1882 by Gunson 

 Thorpe in irrigation creeks near Wuhu in China, some 260 miles 

 up the Yangtse-Kiang \ four years later the same species was 

 found by Prof. Kofoid in the Illinois River, and also by Prof. 

 H. G. Jennings in a pool close to Lake Erie in America. 



Tetramastix opoliensis, first discovered by Prof. Zacharias in 

 1897 in water from the Oder near Oppeln, in Germany, was found 

 by me four years ago in a pool in the Matoppos, Rhodesia ; then 

 it was obtained in Bohemia by Hlava, and lately in France by 

 Dr. de Beauchamp. 



Lacinularia natans, a free-swimming form, was first found by 

 Mr. Geo. Western at Shepperton, near London ; and some years 

 later in Victoria, Australia, by John Shephard, and not since. 



Lacinularia elliptica was first discovered in Australia by 



