72 MR. 0. ARNOLD AND DR. C. L. BOULENGER ON 



About a mile above its junction with another small stream, the 

 Nongqua or Noonka, the ISTorquane River is broken by a large 

 granite bar which during the rains forms a small waterfall. No 

 jellyfishes were seen above this bar, but clown to the junction 

 of the two streams all the pools contained them. The vegetation 

 of the latter consists of water-lilies and Potamogetons together 

 with a submerged plant (not identified) which forms thick carpets 

 on the bottom. The remainder of the fauna comprises the 

 usual aquatic insect larvae, freshwater crabs, mussels, and two 

 small species of fish. 



The jelly-fish in the living state vary in size from about 

 6-16 mm. in diameter, the depth of the umbrella varying corres- 

 pondingly from 3-6-5 mm. when in the uncontructed condition. 

 They are very transparent ; the tentacles are, however, of a milky 

 white colour and more opaque, whilst the umbrella-edge and the 

 base of the manubrium are of a pale yellowish-white and also 

 slightly opaque. When, therefore, the animal is viewed from 

 above, at a distance of two feet or so, only a central patch 

 is seen separated by a transparent area from an external 

 opaque ring. 



The medusa? move fairly rapidly, at the rate of 12-14 inches 

 per minute ; the tentacles usually take part in the wave of con- 

 traction whereby locomotion is effected, but are sometimes kept 

 extended during the whole phase. The manubrium, or stomach, 

 appears to aid in locomotion, being emptied and refilled with 

 water at each contraction. 



The deeper and larger pools contained far greater numbers of 

 these creatures than the shallow ones : this is no doubt laigely 

 due to the difference in temperature between these bodies of 

 water, the temperature being of course higher in the smaller and 

 shallower pools. Careful observation made it clear that the jelly- 

 fish prefer the cooler waters. This was especially seen in the fact 

 that during the hotter hours of the day, i. e. from about 11 a.m. 

 to 4 p.m., very few medusa? were to be seen near the surface ; they 

 remained at a level of about two feet below the same, where the 

 water was appreciably cooler. In the early morning and in the 

 evening they were as plentiful at the surface as at deeper levels. 



It was noticed that the fish in the stream did not attempt to 

 feed on the medusa? — indeed, some of the smaller fish were seen 

 to swim out of the way of an advancing medusa ; it is probable, 

 therefore, that their stinging powers render them unpalatable. 



Although carefully sought for, no traces of a hydroid stage 

 were found. 



Plate I, shows the appearance of the living animal ; after 

 fixation the natural shape of the medusa is not easily appreciated, 

 preserved specimens presenting the flattened umbrella and widely 

 open mouth so generally associated with the genus Limnocnida. 



The specimens received in England had been fixed with various 

 reagents, chiefly corrosive sublimate and osmic acid : all, unfor- 

 tunately, had the umbrella edge, the tentacles, and the manubrium 



