1G6 BULLETIN OF THE 



function the retraction within the involucruni of the extremity of the knob. 

 They are shown in Fig. 20, d. 



Eudoxia Lessonii, Huxlbt. 



Plate VI. Figs. 8, 9. 



In my paper on the Siphonophorae (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, Gegenbaue. 



Plate VI. Fig. 12. 



In the figure given of this medusa, organs corresponding to those in E. Les- 

 sonii have the same lettering. 



DISCOPHORA. 



Cyanea arctica, Eschscholtz. 



G. arctica is one of the more abundant jelly-fishes in Narragansett Bay. 

 Three species of Cyanea called C. arctica, Per. & Les., G. fulva, Ag., and G. 

 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 G. versicolor, do not seem of sufficient importance to 

 call for their separation. Difi"erences in color in this as in many other Dis- 

 cophorm may be the results of individual, seasonal, or sexual variations. 



The Ephyra of C. arctica. 



Very little is known of the ephyra of G. arctica. It has not been figured by 

 Prof. Agassiz, and the representations by others are imperfect and few in num- 

 ber. It diff'ers very greatly from the ephjTa of our other common Discophore, 

 Aurelia, and on that account I have introduced figures of it here. The genus 

 Gyaneopsis of Brandt is an ephyra of Gyanea, as a comparison of the figures which 

 I have given with his will, I think, make evident. The latest figures which 

 have been published of the ephyroD of discophorous medusae are those in an 

 excellent paper by Claus,* of the genera Aurelia, Clirysaora, and Pelagia. In 

 Agassiz's " Contributions " are excellent figures of the ephjrra of Aurelia. No 

 representations are found in either of these works of the ephyra of Gyanea. 

 Agassiz gives a short de.scri])tion of the young of this genus, but of a stage con- 

 aidcraljly older than that which I discovered. 



The youngest ephyra of C. arctica wliich was captured was caught with 



* Studien iiber Polyiitu und Qualleu der Adiia. 



