142 Proceedings of the Royal Physical Society. 



these appeared to be one circular gonad ; and Hargitt (I.e., p. 565) alludes to 

 " the not infrequent occurrence of signs of atrophy " of gonads. He gives a 

 figure of a specimen of which he says, " It will be observed that associated 

 with the small size of the pouch and gonad is the entire absence of the inter- 

 radial canal and its marginal organ " (I.e., p. 565). 



Summary. 



1. There may be " local races " of Aurelia aurita. 



2. The rate of growth is very rapid. 



3. About 16 per cent, have a variable number of tentaculocysts. 



4. The range of variation is from 4 to 16 tentaculocysts for one individual. 



5. The variation is distinctly towards an increased number of tentaculocysts. 



6. The marginal system is connected with the central system by means of 



radial canals, but there is a lack of correlation between the sensory 

 system and the reproductive system. 



7. About 2 per cent, have an abnormal number of genital organs. 



8. The range of variation for gonads is from 2 to 6 for a single individual. 



9. The variation is distinctly towards an increased number of gonads. 



10 There is a very close relation between the number of oral lobes and the 

 number of genital organs. 



11. There is a very definite correlation between the number of branched 



radial canals and the number of tentaculocysts. 



12. The perradial canal system (the first in order of development) is much 



the more variable of the two branched canal systems. 



13. Examples of Aurelia aurita from the Clyde with 10, 12, 14, or 16 



tentaculocysts (or branched radial canals) are more numerous than 

 those with 9, 11, 13 or 15 tentaculocysts (or branched radial canals). 



14 About one per cent, have twin -tentaculocysts. 



15. The twin-tentaculocysts are usually situated at the bases of perradial 



canals. 



16. The characteristic radial symmetry of a normal Aurelia aurita may be 



changed, owing to the absence of correlation amongst certain sets of 

 organs, to bilateral symmetry. 



17. Asymmetrical forms are comparatively few. 



