138 BULLETIN OF THE 
arranged on the'surface, and not concentrated, as in O. maculata, into prominent 
areas, The spots are most conspicuous when the medusa is seen from the 
aboral region. When the Ocyroé is seen from the side, and not from above or 
below, only two of these areas cau be observed, 
In general profile O. maculata resembles Bolina. The oral lappets are, how- 
ever, much more developed, and when expanded are carried at a right angle to 
the axis of the medusa. At its distal end each lobe divides into two wings, 
which narrow until they become pointed. Plate IV. fig. 3. 
The medusa is very active in its movements. The motion is due to the 
“jerky” contraction of the oral lappets. The quick contraction of the muscular 
areas forming the conspicuous brown “spots” is the main cause of this violent 
motion of the oral lappeta. 
The chymiferous tubes of the oral lappets have a very tortuous course, es- 
pecially in that part of their extent near where they join the base of the auricles. 
The rows of combs differ but little from those of Bolina, except from the 
great development of the oral lappets, four are relatively much longer than the 
remainder. 
The auricles are longer than in Bolina. The tentacles, if present, are short 
and inconspicuous. 
This description is made up wholly from drawings and notes by Mr. Agassiz. 
I have never seen O. maculata. 
St. Vincent and Barbados, 1879, March. 
DISCOPHORA. 
Dodecabostrycha dubia, BRANDT. 
A Discophore closely allied to Dodecabostrycha dubia, Br. was obtained by 
Mr. Agassiz * in the Gulf Stream, in the summer of 1880, 
Bell low, disk-shaped, with thin walls. The interior in alcoholic specimens 
is filled by a dark purple mass composed of sexual tentacles, ovaries, and 
stomach. At the apex there is a slight prolongation of this mass into the bell 
substance, resembling the “scar” on the apex of the bell of a young hydroid 
medusa, where, however, it is the remnant of an attachment to a hydroid. 
The lower part, or margin of the bell, is very much enlarged, forming the 
marginal lobules, which hang down on the rim far below the point of insertion 
of the tentacles. The marginal lobules are supported by sword-shaped bodies, 
blunt at one end and tapering at the other, which is their distally placed ex- 
tremity. Each lobe is supported by one of these structures, which is medially 
placed as regards the lobe. The number of tentacles is twelve, while the num- 
ber of marginal lobules is sixteen. The tentacles arise in theincisions between 
the marginal lobules. 
The otocysts are four in number, and spring, like the tentacles, from the in- 
Letter to Mr. C, P. Patterson, No. 4, Bull. M. C. Z., Vol. IV. No. 8. 
