122 J. W. Hewkes—Medusa from New England. 
Oral arms.—From the central region of the umbrella there 
hangs a complicated oral apparatus known as the Mundscheibe. 
The general form of this region is pyramidal or more like the 
frustrum of a cone. 
The oral region of the medusa consists of a consolidated por- 
tion, oral cylinder, next the subumbrella, by which it is joined 
to the bell, and a more distal part composed of eight separate 
oral arms. It was impossible for me to study the structure of 
the basal region, or oral cylinder of the Mundscheibe for the 
reason that it was broken from its attachment so that the union 
could not be observed. At the same time it was for the same 
reason impossible for me to observe the character of the genital 
cavities and the central gastral cavity, structures which present 
most importaut characters in the study of the Rhizostomide. 
The wall in the region of the mouth opening was also ruptured 
so that it was impossible for me to observe whether it really 
exists. Portions of the genital glands were found clinging to 
the basal region of the Mundscheibe, but their true form and 
relation to other organs could not be determined. ‘The distal 
region of the mouth-apparatus is the best preserved of all the 
fragments which were studied. These are markedly peculiar 
and different from the same structures in other medusee which 
have been figured. ‘ 
Two different sets of appendages to the oral cylinder make 
up the distal extremities of the oral apparatus. The longest 
of these, eight in number, are direct continuations of the oral 
cylinder, and will be known as the oral arms. The second 
set of appendages are shorter than the former and are sixteen 
in number. These will be described as the scapulettes. 
The oral arms are gelatinous, more or less angular appen- 
dages, arising from small supports, and gradually broadening 
and enlarging towards their free distal ends. Near their free 
extremity they subdivide in fleshy, gelatinous lobes, along the 
edges of which are sucker-like structures, which will be 
described as sucker-frills. The outer or abaxial region of the 
oral arms is smooth, rounded, angular, the gelatinous wall 
being rather thick. On the axial side the gelatinous substance 
of the oral arms thins out, and along the margin the lobes bear 
sucker-frills. Hach oral arm is generally irregular, trifid, and 
in some cases we find a large number of gelatinous lobes at the 
distal end of the arm. When the arm has three lobes, two of 
these lobes were observed pointing abaxinlly and one axially. 
Along ‘the free edges of these lobes there extends a thin, mem- 
branous structure with small papillz or pigmented projections. 
These membranous folds are mouths, and from their form are 
called the sucker-frills. Those frills on the two outer lobes 
are known as dorsal frills; those on the axial, the ventral frills. 
