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PROCEEDINGS OF THE 



[Dec, 1857. 



terised by the unusual proximity of its paired ambulacra, giving 

 the appearance of four, instead of eight. The Cydippe brevicos- 

 tata of Will, is, perhaps, the young of Eucliaris multicornuta* 



Another class of facts connected with the multiplication of 

 individuals among Ctenophorous Medusae, has been presented to 

 my attention from time to time in a somewhat disconnected man- 

 ner. These facts appear to indicate a peculiar kind of fissipari- 

 tion, and are principally as follows: 



I had repeatedly observed, that in tolerably active full grown 

 Bolinas, there occurred, under conditions which I do not profess to 

 understand, a sort of shedding of the ambulacra — a tendency of 

 the outer surface to break up into small fragments, which certainly 

 did not at once lose their vitality. During the exhibition of this 

 phenomenon, also, the original animal did not appear to lose its own 

 vitality for some time, and its subsequent death, which, so far as 

 my observations went, always took place, has appeared to me to 

 be rather due to the adverse circumstances by which specimens in 

 captivity removed from the sea, are always rendered more exposed 

 to the chances of dissolution, than to the dismemberment to which 

 by this process they were subjected. The fragments thus liber- 

 ated, were usually portions of the ambulacra, varying in size, but 

 which immediately assumed a spontaneous motion of their own, 

 the blades remaining in full activity. 



A fragment of the ambulacrum thus separated, contracts, upon 

 the side opposite that which bears the ciliary blades, and revolves 

 with an excentric motion. They vary greatly in size, according to 

 the length of ambulacrum separated in each case, and also accord- 

 ing to the size of the original medusa from which they came. Some 

 have been so large as to be very conspicuous objects, while others 

 have been barely visible to the naked eye. The large examples 

 I have never seen to pass through any changes in my jars — but I 

 think it will he apparent, in the course of what I will relate, that 

 this is probably attributable to the contracted sphere to which they 

 were confined, from which death speedily ensued both to the origi- 

 nal medusa and its dismembered parts. 



On one of the dates mentioned above, however, when I was 



*With deference to the memory of Will, I suggest that the position of 

 the cleft between the labia, in his drawing Plate 1, fig. 16, is an error, since it 

 is not in the same plane with the line of the tentacula, but at right angles to it. 

 Such an error may have resulted from the appearance of a specimen under com- 

 pression. 



