24 MUSEUM, BROOKLYN INSTITUTE OF ARTS AND SCIENCES. 
In additiou to the tentacles there are about sixty-four bluntly rounded 
papilhT upon the bell-margin. 
There are sixtj^-four otoeysts, a pair on either side of the origin of each 
and every one of the short, straight tentacles. Each otocyst contains a sin- 
gle spherical otolith. 
There are four straight narrow radial canals and twenty-eight diverticuhTe, 
which extend inward from the circular vessel, and end blindly in the gelatin- 
ous substance of the bell. The otoeysts flank the sides of these radial canals 
and diverticulje (see Fig. 53). 
The four gonads are papilliform and are developed upon the outer halves 
of the four radial canals (see Fig. 59) 
The manubrium is tubular, cruciform in cross section and elongate, and 
has four recurved lips. It extends about three-quarters of the distance from 
the inner centre of the bell cavity to the velar opening. 
The o-elatinous sul)stance of the bell is of a delicate greenish vellow. The 
entoderm of the manubrium gonads and tentacle bulbs is opaque yellow-green, 
with the innermost parts purple. There are four interradial, reddish purple, 
pigment spots upon the manubrium near the points of origin of the radial 
canals. The nematocyst-warts upon the short tentacles are either white or 
dark purple, while the half-rings on tlie long, flexible tentacles are red and 
yellow. 
Development of Mahim: The youngest medusae (Fig. 50, Plate V) ob- 
served were about 0.7 mm. in diameter, the bell being higher than a hemi- 
sphere and the exumbrella surface regularly besprinkled with nematocysts. 
There were eight tentacles, four radial and four interradial. These all be- 
longed to the short, straight, ''adhesive" set and projected from the sides of 
the bell above the bell-margin. Therc^ wcne only four otoeysts, one at the base 
of each interradial tentacle. The radial canals were narrow and straight- 
edged, and the circular vessel was simple without centripetal diverticula'. The 
manubrium was quadratic, and very short. 
As the medusa grows its bell increases in height relatively faster than 
in width, so that it becomes higher than a hemisi)here and resend)les in shape 
the bell of Bougainvillia. When 3 mm. high (Fig. 51, Plate V) there are 
still only eight tentacles, but the radial canals have become broad with serrate 
edges,and foui'inlcnadial divert icnhe begin todevelop from the circular vessel. 
The eight tentacles have greatly elongated and terminate in simple nematocyst- 
