PROCEEDINGS OF SOCIETIES. 
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Dr. Hudson tlien read a paper, “ Further Researches on Pedalion 
rnira ; a new Six-limbed Rotifer.” 
Mr. Slack said that having had the advantage of seeing specimens 
of Pedalion which Dr. Hudson had kindly seut him, he was in a 
position to state that the results laid before the Fellows that evening 
gave no notion of the immense amount of trouble Dr. Hudson must 
have taken to understand the creatures. Those exhibited before the 
Society that evening were sufficiently hungry and empty to be 
comparatively intelligible. The interior organs of specimens he 
(Mr. Slack) had examined were practically invisible, owing to the 
presence of a quantity of coloured matter, and they did not live long 
enough to permit of their being reduced to the requisite condition of 
attenuation. The creature, in a free-swimming state, exhibits a 
peculiar jerking motion like Triarthrci , which was the nearest approxi- 
mation to it in being furnished with articulated spines. Pedalion’s 
rapid mode of swimming renders it extremely difficult to follow its 
movements. After alluding to the unsatisfactory definition of the 
term Rotifer, Mr. Slack continued : If all the oral cilia were taken 
off from Pedalion, anyone looking at it in that condition would take it 
for a small crustacean. Many naturalists, Gosse among them, had 
pointed out the affinities of Rotifers with Articulata, and certainly 
the creature under discussion approached that type more nearly than 
any that had been previously found. From the perfection of its 
swimming organs and their complexity, there was an evident resem- 
blance to the Arthropodous type of animals. The specimens he saw 
had no active cilia at the tail bifurcations, and it was very probable 
that Dr. Hudson’s explanation that they had been shed was correct. 
Mr. Lowne said he thought that some forms of Arthropodous 
Rotifers had been described in Kolliker’s ‘ Zeitschrift ’ about twelve 
months ago. These rotifers had what he (Mr. Lowne) took to be 
Arthropodous legs, and the interior arrangement of the animal had 
been set forth in nearly the same words as those Dr. Hudson had 
used in describing Pedalion. The memoir was written by a Russian. 
Mr. Stewart said he thought it possible there might be some 
difficulty in distinguishing between the Rotifers and some of the more 
minute forms of Crustacea. He would only mention one of the defini- 
tions to be found in text-books, namely, that no crustacean has, in any 
parts of its body, cilia ; whereas these creatures which Dr. Hudson 
had described in his admirable paper had articulated limbs, and the 
great majority of them had cilia, although some exceptional forms 
might be deprived of them. 
Dr. Hudson said he had seen the drawing referred to by Mr. Lowne ; 
it had been published shortly after he (Dr. Hudson) had made his own 
public ; but it differed essentially (as he demonstrated by figuring it) 
from Pedalion. This creature, as to its classification, he would place 
simply among Arthropoda, hollow-limbed animals. What, broadly 
speaking, was the difference between a worm and an insect ? It was 
the homonomy of one and the heteronomy of the other. Take a trans- 
verse section of a worm and you get the sections repeating themselves 
throughout the extent of the form ; but in the transverse sections of 
