DACTYLOMETRA QUINQUECIRRA. 49 



of the smaller lobe, the shorter tentacles being placed nearest the eyes. 

 There are eight marginal lobes in which the eyes are placed, eight 

 large lobes in the middle of the space between the eyes, from which the 

 large tentacles arise, and the space between this large lobe and the 

 lobe of the eye is occupied by the small lobes on the sides of which 

 the smaller marginal tentacles are placed, making in all thirty-two 

 marginal lobes. The fringes of the actinostome extend in four simple 

 thick lobes, with frilled edges, about twice the length of the transverse 

 diameter ; they are flesh color. The ovaries are seen from above as 

 four large yellow bunches. These Medusae are nocturnal in their hab- 

 its ; they are only occasionally found floating at the surface during the 

 day, while at night, in the same localities, the bottom swarms with 

 these large masses of dull phosphorescence, moving about with the 

 greatest rapidity. When kept in tanks, they remain torpid during the 

 day at the bottom of the jars, and when night comes on begin to 

 become more animated, and soon move briskly about, emitting a dull 

 phosphorescent light. This Pelagia is always accompanied by a spe- 

 cies of Clupeoid, found in the folds of the fringes of the actinostome, 

 moving along with the jelly-fish, which, when they are pushed off 

 accidentally, rush back to their place of shelter. From twenty to thirty 

 specimens have been found swimming in the fringes of the actinostome. 

 It is strange that the fish should go there for shelter, for every once in 

 a while one of them pays the penalty by being swallowed, without this 

 disturbing the others in the least ; they in their turn find food in the 

 lobes of the actinostome, and even eat the folds themselves, until their 

 turn comes to be used as food. I have seen in this way three fishes 

 eaten during the course of as many days. The specimens measured 

 about an inch in length. Sars, Leuckart, and Peach have observed this 

 same kind of parasitism of certain species of fishes upon other Dis- 

 cophoroe. Nor is this limited to Acalephs ; some species of Holothu- 

 rians, and even a Culcita, are said to give refuge to fishes. 



It is somewhat strange that almost all the Medusae which have been 

 observed are found in the brighest sunshine only, or in very dark 

 nights. Early in the morning, and till about ten o'clock, even on clear 

 days, Medusae do not make then: appearance, while from eleven till one 

 or two o'clock they can be caught in abundance. After that time they 

 disappear gradually, and late in the afternoon, towards sunset, it is rare 

 to see a single jelly-fish. Between nine and twelve o'clock at night, 

 they come to the surface again ; and that hour, in fact, is one of the 

 most favorable for collecting, in spite of the darkness. 



Nantucket Bay (Desor) ; Naushon (A. Agassiz) ; between Bermudas 

 and Azores (J. Dray ton). 



Cat. No. 343, Naushon, Mass., Sept. 1861, A. Agassiz. 



Cat. No. 388, Bermudas, A. S. Bickinore. 



NO. II. 



