614 Transactions of the Society. 



glare of a tropical sun, breakers beating on the rocks below within 

 twenty feet of it, with no life to be seen but the eagle soaring over- 

 head, and no sound to be heard but the mournful cry of the dingo as 

 the sun goes down ; and yet, strange to relate, I found the water of 

 such a solitary and apparently lifeless pool * literally swarming with 

 the wonderful Pedalion. 



It was whilst examining the water of a pond in the picturesque 

 gardens of the Acclimatization Society, Brisbane, in February 1887, 

 that I noticed the presence of a number of tiny white globes swimming 

 freely in the water, which I at first took for Conochilus volvox. 

 Further examination convinced me that I had found a new species of 

 Megalofrocha, an opinion afterwards confirmed by Dr. Hudson, to 

 whom I am indebted for much kind help and encouragement. He 

 proposed the name of Megalotrocha semihullata, since it carries but 

 half the number of opaque warts which adorn the body of M. albo- 

 jiavicans, hitherto the only known species of this genus. 



The following are the specific characters of this new Eotiferon : — 



Sp. Ch. — Cluster spherical, free-swimming, consisting of many 

 adults and their young. No coherent gelatinous tubes. Corona 

 somewhat quadrilateral, the axes being nearly equal ; oblique, and 

 looking towards the dorsal aspect. Ventral sinus shallow. Trunh 

 with two opaque warts, one on each shoulder, on the ventral surface 

 below the corona, and between it and the ventral antennae. Ventral 

 antennss below the corona and the opaque warts, as two small 

 setigerous pimples, standing on the arched ventral surface. Dorsal 

 antennm absent. Eyes two, bright red, on the upper edge of the 

 dorsal surface of the ciliary wreath, between the inner and outer 

 rows of cilia. 



From the above brief description it will be seen that the resemblances 

 to the only known species of this genus, viz. M. alboflavicans, are 

 (1) the possession of opaque warts on the ventral surface below the 

 corona ; (2) the dorsal position of the gap in the ciliary wreath (gen. 

 ch.) ; and (3) the absence of gelatinous tubes. The differences are — 

 (1) the possession of eyes in the adult individual ; (2) the possession 

 of antennae ; and (3) in the fact that it is free-swimming. These 

 differences will therefore cause some alterations in the generic 

 characters. 



The cluster, consisting sometimes of as many as seventy individual 

 is perfectly visible to the naked eye, and is about 1/20 in. in diameter ; f 

 each individual being about 1/40 in. when fully grown. Although 

 I examined the leaves of the water-plants very carefully, in no instance 

 was I able to recognize any attachment to the leaf. 



The general anatomy of the individual rotiferon resembles in the 

 main points that of M. alboflavicans, but a few points require special 

 notice. 



* This promontory will be kuown in future Admiralty charts as Pedalion Point, 

 i)unk Island. 



t A mounted specimen under pressure measured 1/12 in. in diameter. 



