166 BULLETIN OF THE 
function the retraction within the involucrum of the extremity of the knob. 
They are shown in Fig. 20, d. 
Eudoxia Lessonii, Huxvey. 
Plate VI. Figs. 8, 9. 
In my paper on the Siphonophoræ (Bull. M. C. Z., Vol. VI. No. 7) a speci- 
men of E, Lessonii is mentioned as taken near Newport. That mention is here 
supplemented by two figures of the medusa. 
Diplophysa inermis, GEGENBAUR. 
Plate VI. Fig. 12. 
In the figure given of this medusa, organs corresponding to those in E. Les- 
sonit have the same lettering. 
DISCOPHORA. 
Cyanea arctica, EscuscHoLtz. 
C. arctica is one of the more abundant jelly-fishes in Narragansett Bay. 
Three species of Cyanea called C. arctica, Per. & Les., C. fulva, Ag., and C. 
versicolor, Ag., have been described from the eastern coasts of the United States, 
by Prof. Agassiz. The main points of difference between C. arctica and the 
other species, C. fulva and C. versicolor, do not seem of sufficient importance to 
call for their separation. Differences in color in this as in many other Dis- 
cophoræ may be the results of individual, seasonal, or sexual variations. 
THE EPHYRA OF C. ARCTICA. 
Very little is known of the ephyra of C. arctica. It has not been figured by 
Prof. Agassiz, and the representations by others are imperfect and few in num- 
ber. It differs very greatly from the ephyra of our other common Discophore, 
Aurelia, and on that account I have introduced figures of it here. The genus 
Cyaneopsis of Brandt is an ephyra of Cyanea, as à comparison of the figures which 
I have given with his will, I think, make evident. The latest figures which 
have been published of the ephyræ of discophorous medusæ are those in an 
excellent paper by Claus,* of the genera Aurelia, Chrysaora, and Pelagia. In 
Agassiz’s * Contributions” are excellent figures of the ephyra of Aurelia. No 
representations are found in either of these works of the ephyra of Cyanea. 
Agassiz gives a short description of the young of this genus, but of a stage con- 
siderably older than that which I discovered. 
The youngest ephyra of C. arctica which was captured was caught with 
* Studien über Polypen und Quallen der Adria, 
