34 



NOTES ON AN ABNORMAL EPHYRA OF 

 CYANEA CAPILLATA. 



By JOYCE HILDRETH EOBSON, B. Sc. 



On February 27th a large yellow ephyra, measuring 2 milli- 

 metres in diameter, was observed in the codling tank amongst the 

 Aurelia aurita epyhra. 



It had eight arms, six of which were of the normal ephyra 

 formation, viz., two-lobed, with one sense organ between the lobes. 



The other two arms were opposite ; they were each composed 

 of three lobes, with two sense organs between them ; the middle 

 lobe was indented, and at first only half the length of the other two, 

 but rapidly grew until it was double their size. A band of clear 

 yellow tissue in the sub-umbrella, stretching from the base of the 

 arm to the centre of this third lobe, seemed to act as a kind of tendon, 

 for the third lobe was generally depressed, making an angle 

 with the plane of the arm varying from 80°-20° or less. 



Irregularities in the distribution of the sense organs were also 

 observed. The six normal arms had each one sense organ between 

 its two lobes, as is usual ; but one of these arms had also two sense 

 organs close together about halfway between the base and aj3ex of 

 the arm, to one side of the middle line (fig. la). The same thing 

 was noticed in one of the two abnormal arms, while the other arm 

 of this pair had a single organ in the same position (fig. 16). The 

 former arm had in addition two sense organs to one side of the 

 third lobe (fig. lc) instead of one, making a total of five sense organs 

 for that arm, and three for the other. 



Between the arms the tentacles were just beginning to grow 

 out, showing as brownish buds (fig. 1). 



The ephyra was placed in a glass tank, with a number of 

 Aurelia eph}Ta and small medusoids. It was not observed to eat 

 any of these till April 2nd, when a small Aurelia, about one-third 

 its own size, was noticed caught in its manubrium (fig. 5). Next 

 day this was reduced to half its size, while it was entirely digested 



