St. Andrews Marine Laboratory. 301 



Thaumantias maculata, Forbes. 



In June this form well illustrated the variability of a species 

 in regard to maturity. Specimens were very numerous and 

 very ripe on the 23rd, while those obtained on the 25th were 

 immature. At the beginning of July they were almost ripe and 

 fully half an inch in diameter, and a week or two afterwards 

 others of the same size were mature. This variability in 

 regard to maturity probably depended on the stage of growth 

 of a particular series, which it may be was swept by currents 

 into the bay. 



Forbes found this Hydromedusa several times in Bressay 

 Sound, Shetland. It was never plentiful. 



Thaumantias gibbosa, Forbes. 



Many examples apparently of this form were procured in 

 the midwater-net on the 13th and 18th June. 

 Forbes captured it in the Hebrides. 



Thaumantias pileata, Forbes. 



A few specimens referable to this species were procured at 

 the beginning of June. 



It was discovered by Forbes at Portrush, on the north 

 coast of Ireland, in June 1839. 



Thaumantias hemisphcerica (Gronovius), O. F. Miiller. 



This, perhaps, is the most conspicuous of the group both 

 in regard to size and numbers in June, and it is often stranded 

 on the West Sands in great profusion, and nearly 1 inch in 

 diameter. Moreover it has an additional interest, since it is 

 frequently selected by the larval Peachue for attachment by 

 the widely open mouth and tentacles. The young anemones 

 are thus carried about without effort on their part, and obtain 

 some of the advantages of the Arachnactis-st&ge of Edwardsia. 

 T. hemisphcerica reached full maturity this month. During 

 July it was in great profusion in the midwater-net and occa- 

 sionally appeared in the bottom-net ; and since the latter 

 feature did not occur previously, it may be presumed that it 

 was not entirely due to the capture of the Medusoids on the 

 way up. Larval anemones (Peachice) now considerably larger 

 still adhered to this species and to T. melanops, occupying 

 diverse positions, as on the outer surface at the margin of the 

 base or on the manubrium. The Hydromedusa? were also 

 often fully ripe. Some of the larger exceeded f inch. 



Small examples were common in the bottom-net in August, 



