Edward T. Browne 
99 
the normal type and probably due in many cases to the outward growth of the 
genital sacs cutting off the base of the canal. Instead of one canal leaving the 
stomach there are three. The central one runs direct from the stomach to the 
tentaculocyst and the lateral ones are branched. 
The adradial canals are always simple and unbrauched and never run to a 
tentaculocyst. 
Specimens which have less than the normal number of tentaculocysts have 
usually a corresponding decrease in the number of branched radial canals. If one 
perradial tentaculocyst be absent, the branched canal is also absent and its place 
taken by a simple unbranched canal. The loss of one or more branched canals 
does not produce a vacant space, the adjacent branched canals spread out and 
occupy a larger area. 
A decrease in the number of tentaculocysts may occur through injury done to 
the umbrella. This can, as a rule, be detected by a careful examination of the 
margin with a lens. The presence of a branched canal without a tentaculocyst is 
suspicious, and if there were any traces of an old injury which had healed up, 
leaving a slight or an irregular margin to the umbrella,, the specimen was rejected 
as a damaged one. 
In a few specimens a branched canal without a tentaculocyst was found with 
the margin in a perfect condition and these were considered cases of genuine 
variation. 
Anastomosing of the radial canals by cross branches forming a kind of net- 
work occurs in nearly all the large adults. It is rarely present in the small adults. 
The amount of anastomosing is very variable and not always regularly distributed 
amongst the radial canals. Often one or two quadrants in a specimen show 
considerable anastomosing, whilst the other quadrants are comparatively free 
from it. In two specimens, having the same sized umbrella, one may show a 
considerable amount of anastomosing, the other practically none at all. The 
adradial canals are often anastomosed to the branches of the perradial and inter- 
radial canals. 
The Position of the Tentaculocysts in Specimens liaving a Decrease in 
Niunher. 
In my previous publication on Aurelia there is a sentence which is rather 
misleading and requires an explanation. " An examination of the specimens 
(adults) does not show that any particular position on the margin of the umbrella 
is favoured either by an increase or decrease of the tentaculocysts." If the position 
of the tentaculocysts on the margin of the umbrella were marked down on skeleton 
diagrams, no attention being paid to the radial canal system, then the above 
statement would be correct. The material upon which that statement was based 
(adults of 1894) was not in first class condition and no attempt was made to 
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