MEDUS.K. :57 



position of the gonads upon the radial canals is slightly variable. Some specimens 

 have the gonads extending over the proximal half of the canals, and others over the 

 central third portion of the canals. There is always a space between the stomach and 

 the gonads, so that the species cannot be placed in the genus Isonema of Maas, which 

 has the gonads adjacent to the stomach. 



One specimen still retains most of its tentacles, but the other specimens have, as 

 usual, lost their tentacles, and only the stumps remain. The tentacles are long and 

 thread-like, and have more the appearance of long cirri. They are too macerated for 

 a detailed description of their structure. Sense organs were searched for, but not 

 found. 



NAECOMEDUS.E. 



FAMILY ^EGINID^E (GegenBaur, 1856), Maas, 1904. 

 SOLMUNDELLA (Haeckel, 1879), Maas, 1904. 



Generic Character. JLginidaj with two tentacles, and with a stomach having 

 right pouches. 



Prof. Vanhoffen (1908), in his revision of the Narcoruedusse, recognises only one 

 species for the genus, namely, SolmuncJella bitentaculata. (Quoy et Gaimard), 1833. 

 Under that name all the Solmundellse taken by the ' Valdivia ' on her long cruise 

 (1898-1899) in the North Atlantic, South Atlantic, Antarctic, and Indian Oceans have 

 been placed. 



Prof. Maas, on the other hand, recognises two species, S. bitentaculata and .\ 

 mediterranea (Joh. M tiller), 1851. The latter species Maas (1906) has also recorded 

 from the Antarctic, where it was taken by the ' Belgica.' 



The differences between the two species, according to Maas, are the shape of the 

 umbrella, colour, and the number of sense organs. S. bitentaculata has a rather high 

 conical umbrella, with its apex above the exit of the tentacles, and the fully grown 

 adult has sixteen to thirty-two sense organs. S. mediterranea has a rather fiat-topped 

 umbrella, not usually extending above the level of the exit of the tentacles, and the 



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sense organs do not exceed eight in number. 



Dr. Bigelow (1909) points out that the number of sense organs would be the brsi 

 character to select for the distinction of the two species. S. bitentaculata, however, 

 passes through a stage with eight sense organs, and the number increases with age, so 

 that at an early stage it resembles S. mediterranea. 



I became familiar with N. bitentaculata in Prof. Herdmau's collection of Medusae 

 from Ceylon, and after a prolonged second examination of the Solmundellse in the 

 ' Discovery ' collection, I came to the conclusion that S. mediterrant'ti is a distinct 

 species. About twenty of the largest adult specimens in the ' Discovery ' collection 

 were specially examined for the number of sense organs. I could not find more than 

 eight, and they are distinctly adradial. S. bitentaculata of a similar size would have 



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