282 
the disc-margin, and the disc is flattened, while A. limbata is nearly 
hemispherical (see Addenda). 
The perradial canals are branched trichotomically as in A. 
aurita and flavidula, the main-canal sending out near its base two 
branches, which also divide; but in A. aurita and flavidula typ. 
the main-canal does not branch further on; on the other hånd, in 
the specimens from the “Tjalfe” the perradial main-canal sends 
out numerous branches to both sides, repeatedly anastomosing with 
the other branches (see the figures). — In A. aurita, usually 
3 canals issne from every genital sinus; two adradial unbranched 
and one interradial trichotomically branched in the same manner 
as the perradial canals, viz. two side-branches, branching further 
on, and a main stem, usually unbranched; rarely there is one pair 
of eradial slightly branched canals also. — In the typical A. flavi¬ 
dula 7, seldom 5 canals issue from the genital sinus, viz. 2 ad¬ 
radial unbranched, 1 interradial unbranched, 4 (2) eradial branched, 
two on eacli side of the interradial canal, between this and the 
adradial canals. However, the number of eradial canals is of less 
importance, because in younger stages of development the eradial 
canals are seen to be sidebranches on the interradial main-canal. 
— Ia the large specimens from the “Tjalfe” (see fig. 4) 5 canals 
issue from the genital sinus: two adradial, unbranched except in 
their distal part, where they anastomose with the branches of the 
other canals; one interradial, trichotomically branched in the same 
manner as the perradial canals, the main-stem, accordingly, with 
many side-branches; finally two eradial branched canals, one on 
each side of the interradial canal. In younger specimens (fig. 3) 
these two canals issue as side branches from the base of the inter¬ 
radial stem, the same character which is permanent in A. aurita. 
The colour of the living animal is yellow or brownish yellow; 
the preserved specimens are perfectly colourless. 
It will be seen that the characteristics of the Greenlandic 
form of Aurelia refer to A. flavidula as the nearest related form, 
though the Greenlandid form seems to be further developed in 
regard to the mode of branching of the canal system. 
