MUSEUM OF COMPARATIVE ZOOLOGY. 169 
of the ephyra. One of these is always in advance of the others in time of ap- 
pearance, and is the longest. This predominance of one of these marginal ap- 
pendages is another expression of bilateral symmetry, which, as has been pointed 
out by others, is well marked in the tentacles in the younger scyphistoma stage 
of Cyanea and Aurelia. 
In the ephyra in which there are eight tentacles on the margin of the um- 
brella, octants of which I have represented, Plate VII. figs. 9, 10, the resem- 
blance to the members of the family of Pelagidæ is very striking. Not only in 
the outward form is this likeness apparent, but in the internal anatomy the 
resemblances are very close. One of the most striking of these anatomical like- 
nesses is to be seen in the course of the chymiférous tubes in the sense octants 
of these two forms. If one will compare Fig. 9 with a sense sector of Pelagia 
cyanella, he will find the tubes almost identical in their course. The addition 
of new tentacles on the margin of the umbrella of the ephyra takes place by 
the growth of new tentacles on either side of that first formed, and in pairs, one 
on each side at the same time. These grow along two sides of a V-shaped 
figure, in which the first formed tentacle is situated at the angle of the V, and 
is directed towards the centre of the ephyra. "The subsequently formed tenta- 
cles to the primary always arise external to those already developed. Marginal 
tentacles in all stages of growth, from a bud to a well-developed filament, ar- 
ranged along the figure of which I have spoken, are shown in Plate VII. fig. 8. 
The same figure shows also the changes which have taken place in the contour 
of the rim of the sense octant, and the greater development of the bundle of 
sexual tentacles. The specimen from which the drawing was made was not 
raised from the larval ephyra, but was taken free swimming in the dip-net. 
In some of the older forms following the ephyra stage, the upper surface of 
the umbrella is covered with peculiar undescribed filaments. - These are well 
shown in a young Cyanea somewhat older than that, an octant of which 
is figured, Plate, VII. fig. 7. This stage with the filamentous appendages is 
shown, Plate VII fig. 1. The whole upper surface of the umbrella is covered 
with peculiar tentacles of unknown function. They are most developed in 
younger stages, but are not wholly wanting in the adult, The filaments to 
which I refer were first noticed in these young Cyanee by Dr. Walter Faxon. 
Of the anatomy of these filaments there is very little to be said. They are 
very flexible, transparent, of brownish color, tapering uniformly from base to 
extremity, and seem to be simple prolongations of the substance of the bell, 
covered by a layer resembling that which is stretched over the whole of the 
aboral surface of the umbrella. They are also solid, and destitute of lasso-cells. 
Their superficial layer is penetrated by those same nerve cells which are found 
all over the surface of the umbrella, the histology of which‘has been so elabo- 
rately investigated by Dr. Eimer. These cells are undoubtedly connected with 
sensation of some special kind, and we may consider with great probability that 
the aboral filaments are specialized sense organs. I suggest for them, whatever 
their function may be, the name of “aboral papille." In some genera of Dis- 
cophore the same appendages also exist, but they are nowhere as prominent as 
