1904 - 5 .] Report on Medusae found in Firth of Clyde. 765 
of Fabricius (1780). It was not the type species of the genus 
Melicerta, but was considered so by Oken in 1835. 
Fabricius’s description of Medusa campanula is rather vague, 
and no figure is given. In the description there is no mention 
made of eight radial canals and eight gonads, but the description 
implies only four radial canals, and this was the view held by all 
the early writers. Lamarck (1817) transferred it to the genus 
Dianoea , and Lesson (1843) to the genus Campanella , and re-named 
the species C. fabricii. Up to that date the early authors had 
simply been dealing with the original description given by 
Fabricius, who found the medusa on the coast of Greenland, and 
they themselves had not seen a single specimen. 
In 1862, L. Agassiz called a medusa which he found at Grand 
Manan in the Bay of Fundy, Melicertum campanula , Peron. In 
1865, A. Agassiz described and figured specimens found in 
Massachusetts Bay. This medusa has eight radial canals, and is 
very like the species first found by Sars. There is no evidence 
whatever that Agassiz’s medusa has any connection whatever with 
Fabricius’s medusa. Haeckel was also of this opinion, for he has 
placed Medusa campanula , Fabricius, as a doubtful synonym of 
Catablema campanula. 
Haeckel, however, has retained the genus Melicertum for 
Melicertum campanula of Agassiz, and he has defined the genus 
thus 
“ Melicertum , A. Agassiz, 1862. Thaumantidae with eight gonads 
on the course of eight radial canals. Numerous tentacles (sixteen 
or more). No marginal clubs or cirri.” 
Melicertum has really become a new genus, and with a new type 
species, M. campanula , A. Agassiz (non Fabricius). 
Haeckel (1879) introduced a new genus, Melicertidium , for 
Oceania octocostata , Sars, 1835, and defined the genus thus : — 
“ Thaumantidae with eight gonads on the course of eight radial 
canals. Numerous tentacles (sixteen or more). Between them 
numerous marginal clubs (or cirri). 
Haeckel himself had never seen a specimen of Melicertidium 
octocostatum , so that his description is based upon the work of other 
writers. He placed a wrong interpretation upon the figures given 
by Ehrenberg, and thought that the small tentacles figured by 
