28 ANNALS OF SCOTTISH NATURAL HISTORY 



ing series of abnormal forms. We find, instead, two 

 regularly decreasing series, one for individuals with 10, 12, 

 14, 1 6, and another for individuals with 9, 1 1, 13, 15 

 branched radial canals and tentaculocysts. The table given 

 also shows that there are 25 individuals with 284 branched 

 radial canals and tentaculocysts in the former series, against 

 15 individuals with 147 branched radial canals and ten- 

 taculocysts in the latter. Looking at these facts in another 

 way we observe that the abnormal examples have an average 

 of 10.5 branched radial canals. Though the details of the 

 branched canal system are not given here, they show that it 

 is in the " perradial " system (i.e. between the gonads) that 

 the increase in the number of canals is greatest. 



Occasionally there are found individuals with twin- 

 tentaculocysts, covered by a small marginal hood, at the end 

 of a single canal. In this collection there were found two 

 examples with this abnormality, and in both cases the twin- 

 tentaculocysts were situated perradially. In one of the 

 individuals this " twinning " was the only abnormality noted ; 

 in the other there were five gonads, ten branched canals, and 

 eleven tentaculocysts. 



(2) On the number of Gonads and Oral Lobes. 



A normal A. aurita has four symmetrically situated 

 genital sacs each with a horse-shoe-shaped gonad, and four 

 oral lobes. The gonads, becoming highly coloured as they 

 ripen, are very characteristic and conspicuous organs. In all 

 the examples I have examined there is perfect correlation 

 between the number of gonads and the number of oral lobes. 

 The following is a summary of the observations made : 



2 specimens had 3 gonads and 3 oral lobes. 

 269 4 >5 4 



4 )) )) 5 11 " 5 " " 



3 )' 11 ^ 11 11 u ,, ,, 



2 55 55 1 11 11 7 11 )) 



T R ^ 



5) 55 55 55 11 11 



From this it is seen that the range of variation for 

 gonads and for oral lobes is from 3 to 8. The solitary 

 individual with 8 gonads measured only 7 centimetres in 



