2 EDWARD T. BROWNE. 
organ is below the average in size, and the tentacles in each 
group are also below the normal number. I have noticed 
among the Ephyre of Aurelia aurita, that when a great 
increase in the number of arms occurs, the arms are below the 
average In size. 
Another specimen has seven groups of tentacles, seven 
colleto-cystophors, seven genital bands and five septa, an 
increase in the number of septa, but a decrease in the other 
organs. 
A numerical variation of the septa only occurs in seven 
specimens (about 44 per cent.) ; four of these are given above, 
and the others, which have only three septa, will be described 
in another part of this paper. I think in all cases the 
numerical variation of the septa may be safely considered to 
be congenital. The septa run nearly the whole length of the 
body, and are not likely to be affected by an external injury. 
In the majority of abnormal specimens the septa have their 
normal number, and the groups of tentacles, colleto-cystophors, 
and genital bands show variation. Usually each set of organs 
shows an independent variation, either in number, shape, or 
position. One specimen, however, with the normal number 
of septa, has seven groups of tentacles, seven colleto-cystophors, 
and genital bands, all of which are symmetrically arranged. 
It is now probably the simplest plan to describe the variation 
in each set of organs separately, and to commence with the 
colleto-cystophors. 
The Variation of the Colleto-cystophors.—In the 
five specimens already described the colleto-cystophors vary in 
number along with the groups of tentacles, and occupy their 
normal position on the margin of the umbrella. But many 
specimens show that the colleto-cystophors vary independently 
of the other organs. 
Four specimens with eight groups of tentacles have nine 
colleto-cystophors. In two of these (figs. 2, 4, and 5) 
the increase is produced by the twinning of one of the colleto- 
cystophors. The other two specimens have the additional 
colleto-cystophor in an abnormal position, One is on the 
