80 ON THE GONADIAL GROOVES OF A MEDUSA. [Jan. 12, 
out to be very difficult to manipulate in the preparation for 
sectionizing. There was a very great amount of contraction of 
the mesogloal tissue, so that the sections are considerably distorted. 
However, the figure shows the limits of the groove fairly well 
with its contained mass of eggs. 
The above account affords pretty conclusive proof, I think, of 
the suggestion that these gonadial grooves function as gonoducts, 
and that it is only sriintn their limits that the sex-cells pass on 
their way to the exterior. Also out of ali the specimens 
examined, only comparatively few, as mentioned before, showed 
anything in the space between the gastric pouch and the central 
gastric cavity, and in all of these the substance lay in the grooves 
themselves. 
Thus Awrelia may be looked upon as possessing ccelomic or 
archenteric derivatives of the nature of primitive gonoducts, 
standing alone in this respect among the Ccelenterata so far as 
we know at present, for the origin of the genital ducts of 
Ctenoplana korotneffii is not yet known. 
It is of interest to note that other observations along different 
lines point to the grooves being connected in some way with the 
gonads. From an examination of a series of specimens of 
different stages in development, including ephyre and small but 
complete smell of about one inch in diameter, the gradual 
differentiation of the gastro-vascular system can be traced. In 
those specimens which show the completely developed gastro- 
vascular canals, there are slight indications of gonadial grooves in 
the floors of the almost fully developed gastric pouches. The latter 
are formed by outgrowths of the central or general gastric cavity 
along the interradii and by inpushings of this same gastric 
cavity along the pervadii. By the last mentioned process the 
main passages of connection between the central gastric cavity 
and the gastric pouches are established. While this process is 
going on, “the gonadial grooves appear as two parallel ridges in the 
ventral wall of each main passage and gastric pouch. From this 
it will be seen that the gonadial grooves are of later appearance 
than the ordinary radial “canals, Their complete differentiation 
is coincident with the final stage in the growth of the gastric 
pouches, and incidentally they approach completion just prior to 
the appearance of the gonads. 
From this we may safely infer that the gonadial grooves are 
not concerned with a nutrient function, but rather that they are 
formed in readiness to discharge their function in connection 
with the gonads. 
‘Thr ough the kindness of the officials at the British Museum, I 
was able to examine a number of Acraspedote medusze in 
January last. As a result of this I am able to record the 
presence of the gonadial grooves in another species of the genus 
Aurelia, viz. oman ried. and in three varieties of Aurelia 
aurita, viz., A. aurita var. japonica; A. aurita var. cruciata ; 
and A. aurita var. colpota. 
