180 



DIPURENA. 



pi'esence of the light reddish-bro-\^ai eye-specks, which become red in 

 the adult, it would be difficult, without very close examination, to 

 distinguish them apart. The tentacles of the adult (Fig. 298) are 

 not as long as those of Sarsia ; they are likewise capable of much 

 greater contraction, being often carried in a club-shaped form, not 

 longer than half the vertical axis of the bell. (Fig. 299.) The acti- 

 nostome is also very different ; the lips (four in number) are quite 

 prominent («', Fig. 300), though often carried in trumpet fashion, at 



the extremity of the digestive cavity (a. Fig. 300), and the spherosome 

 increases greatly in thickness at the abactinal pole. 



Massachusetts Bay, Nahant (A. Agassiz). 



Cat. No. 160, Nahant, Mass., July, 1861, A. Agassiz. Hydromedusa- 

 rium. 



Cat. No. 348, Boston Harbor, May, 1862, H. J. Clark. Medusa. 



Cat. No. 378, Nahant, 1863, A. Agassiz. Medusa. 



DIPURENA McCr. 



Dipurena McCr. Gymn. Charleston Harbor, p. 33. 

 Bipurena Agass. Cent. Nat. Hist. U. S., IV. p. 341. 18G2. 



McCrady established this genus from an investigation of two species 

 of Medusae, which, though having all the characteristics of Slabberia of 

 Forbes, yet differed from it in the position of the sexual organs, which 

 are placed in DijDurena along the digestive trunk, as in Sarsia and the 

 like, while in Slabberia Forbes has figured genital organs along the 



Fig. 298. Adult Medusa, in a natural attitude.' 



Fig. 299. The same Medusa as Fig. 298, with the tentacles contracted. 



Fig. 300. Actinostome of adult Medusa, a, when protruded, trumpet-shape ; a', showing the 

 lips of actinostome. 



