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Proceedings of the Royal Physical Society. 



backwards from the abcauline wall partially divides the one 

 from the other. The orientation of the twins differs from 



Fig. 2. Twin hydrothecse of Selagin- 

 opsis mirabilis. x 40. part. = partition. 



the normal, for the marginal teeth instead of being lateral 

 are adcauline and abcauline. 



Two epizoic Hydroids occurred creeping over the colonies, 

 Filelhcm serpens (Hassall), and Campanularia voluhilis 

 (Linn.). 



