1889.] OF THE EMBRYOS IN AURELIA, 585 
(loc. cit.), from segmenting ova to the fully formed planulz or 
“clistogastrulee.” 
Other Medusz belonging to the Acraspeda carry their ova about 
during the first stages of development. Von Lendenfeld states (Proc. 
Linn. Soe. N. S, Wales, vol. ix.) that in Pseudorhiza “the embryos 
are carried about in pouches suspended in great number from the 
radial canals which run centripetally from the ring-canal. They 
remain there till they are fit to turn into young Scyphistomes.” In 
Stylorhiza (Phyllorhiza) punctata, he says (oe. crt.), «the young 
embryos adhere to the mother’s filaments until they have nearly 
attained the Scyphistoma stage”? The same author describes 
(‘ Zeitschrift fiir wiss. Zoologie,’ 1888, p. 301) in Cyanea anaskala 
and Phyllorhiza punctata a peculiar arrangement of filaments on 
the underside of the arms, by which the embryos appear to be 
nourished. 
P.S., Dec. 9, 1889.—Since writing this article my attention has 
been directed to Ehrenberg’s paper, “Ueber die Akalephen des rothen 
Meeres und den Organismus der Medusen der Ostsee” (Phys. Abhandl. 
Akad. Berlin, 1835). Ehrenberg gives a rough figure of Aurelia 
aurita showing a magnified external view of the pouches and their 
contained embryos (Taf. viii. fig. 1, and Taf. iii. fig. 1); and states 
(p- 197), first, that the brood-pouches are either formed by the 
pressure of the “ Kugeln”’ (i. e. ova and embryos) which collect in 
the groove of the arms, or else are preformed by the mother for 
their reception ; secondly, that the pouches increase in size as more 
embryos crowd in; and thirdly, that when the embryos quit the 
pouches the latter collapse and disappear. 
EXPLANATION OF PLATES LVII. & LVIII. 
In all the figures ect denotes the ectoderm; mes, the mesoglea; end, the 
endoderm ; d, digitelle; and the letter G is placed in the lumen of the groove 
of the arms. 
Fig. 1. An oral arm of Aurelia aurita, covered with the little pouches con- 
taining embryos. The letter m is placed in the cavity of the mouth, 
2. A transyerse section of an oral arm which was entirely without brood- 
pouches. The numerous plications are due to the arm haying been 
crumpled while preserved in spirit. 
3. A transverse section of an arm which had few and somewhat small 
pouches. a@ and 4, two of the pouches containing embryos. 
4&5. Two more sections through the pouches lettered a and 3 in the 
last figure. : 
6. A transverse section through an arm which had numerous and very 
large brood-pouches. Only one side of the section is drawn. ¢, d, ¢, 
and jf, four pouches, each containing a great number of embryos, 
those in e, d, and f being only represented in outline. 
Proc. Zoou. Soc.—1889, No. XXXIX. 39 
