138 BULLETIN OF THE 



arranged on the surface, and not concentrated, as in 0. maculata, into prominent 

 areas. The spots are most conspicuous when the medusa is seen from the 

 aboral region. "When the Oajroe is seen from the side, and not from above or " 

 below, only two of these areas can be observed, 



In general profile 0. 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 lappets. 



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 diff'er 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 0. maculata. 



St. Vincent and Barbados, 1879, March. 



DISCOPHORA. 



Dodecabostrycha dubia, Brandt. 



A Discophore closely allied to Dodecabostryclia dubia, Br. was obtained by 

 Mr. Agassiz* in thtf Gulf Stream, in the summer of 1880. 



Bell low, disk-shaped, Avith 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 sliglit 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 loVje. The number of tentacles is twelve, while the num- 

 ber of marginal lobules is sixteen. The tentacles arise in the incisions 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. 



