100 



ECTOPLEURA. 



The Medusa is exceedingly active, moving very rapidly and inces- 

 santly. Found at Nahant in the latter part of August. 



Fig. 319. 



Fig. 316. 



Fig. 317 



Euphysa is not, as Professor Agassiz has stated, the generation of 

 Medusa3 which become separated from the base of the reproducing 

 tentacle in Ilybocodon. That generation of Medusae are identical with 

 the parent Medusa, as well as the second generation wliich bud from 

 the large tentacle of this first set of Medusae. 



Massachusetts Bay, Nahant (A. Agassiz). 



Cat. No. 452, Nahant, A. Agassiz. 



ECTOPLEURA Agass. 



Ecloplcura Agass. Cont. Nat. Hist. U. S., IV. p. 342. 1862. 



In this genus I would include those species of the genus Sarsia (like 

 Oceania telostyla Geg., Sarsia turricula McCrady, and Sarsia gemmi- 

 fera Forbes) wliich have a short digestive trunk, and in which the 

 pigmentrCcUs arc not concentrated in one mass in the sensitive bulb, 

 but are scattered irregularly through the whole swelling at the base of 

 the tentacles. 



Fig. 316. Euphysa virgulata, seen in profile ; magnified. 



Fig. 317. Probuscis of Euphysa. a, actinostome ; », ovaries ; (/, fatty globules ; magnified. 



Fig. 318. Actinal view of Euphysa, to show the character of the veil, t, the odd long tenta- 

 cle ; t', one of the pair of tentacles ; I", the odd small tentacle. 



Fig. 319. One of the tentacles seen in profile, to show the character of the band of pigment 

 cells, ^, extending along the base of the chyniii'erous tube from the origin of the tentacle, t'. 



