710 Proceedings of the Royal Irish Academy. 



The smallest specimen measured 2 mm. in length, and l^mm. 

 in width. Six tentacles on each of marginal bulbs. Oral ten- 

 tacles twice dichotomously branched. 



The largest specimen was 4 mm. in length and 5 mm. in 

 width. Eight tentacles on each marginal bulb. Oral tentacles 

 3-4 times dichotomously branched. The umbrella is globular 

 in shape. The stomach is situated upon a broad inverted cone- 

 shaped peduncle. The gonads form narrow bands extending 

 from the stomach, along the radial canals, up to the base of 

 the peduncle. The compoimd tentacular bulbs are small and 

 roundish ; of a reddish orange colour in formalin. Ocelli black. 

 In the early stages the peduncle is very small. This Medusa 

 was fii'st found by Porbes and Goodsir at Mull, and later by 

 Haeckel off Handa Island, west coast of Scotland. 

 lyiargelliuni octopunctatum (Sars). 



Li%%ia octopunctata, Forbes, 1848, p. 64, pi. xii. 



RathTcea octopunctata, Haeckel, 1879, p. 97. 



Margellium octopunctatum, Haeckel, 1879, p. 95 ; Browne, 1896, 

 P.Z. S., p. 479. 



Margellium yratuni, Haeckel, 1879, p. 95. 



In 1895, during April and May this Medusa was often a 

 common object in the tow-net ; it was veiy abundant about the 

 middle of April. I was able to collect a large number of speci- 

 mens, and to form a series, showing the development of the 

 Medusa from its earliest free-swimming stage to its maximum 

 growth. The Medusa at its maximum growth has not been 

 previously found in Europe, but only is known from North 

 America, where it has been found and described by Agassiz 

 under the name of Lizzia grata. 



In 1896, during my visit in the summer, the Medusa was not 

 seen. I was surprised to see specimens in the tow-nettings 

 sent to me by the Misses Delap, taken between October 23rd 

 and November 6th. These specimens all belonged to the 

 earliest stage, with Medusa-buds upon the stomach in different 

 stages of development. There appears to have been a sudden 

 Bwarm, which lasted about a fortnight. I have never taken 

 this species in the autumn, nor do I know of any autumn records. 

 It is common in the spring, and has a very wide distribution. 



In 1897, it first appeared in January and disappeared in 

 May ; it was very scarce early in the year, but common in 



