ITS CRUSTACEAN PARASITE. 367 



length, so puckered and confused as to render their 

 disentanglement apparently hopeless ; hut in a few 

 moments we see their graceful folds, all separated, 

 stretching their taper length to a distance of ten 

 inches from their hase, and waving slowly through 

 the water with every contraction of the ever-pulsating 

 umbrella. The colour of these elegant organs is 

 white at their upper part ; hut a faint tinge of rose- 

 red becomes perceptible about their middle, and 

 gradually increases in intensity till it becomes at 

 their extremities a decided pink. This hue, however, 

 seems in some way to be dependent on the will of the 

 animal, frequently becoming stronger or fainter in the 

 course of a few minutes. 



The interior of the peduncle is divided by four 

 perpendicular septa into as many ample chambers, 

 which are visible from above. Other folds of mem- 

 brane partially cross their area, causing them at times 

 to appear six or more in number. From beneath, 

 large round openings are seen communicating with 

 the interior of these chambers, into which the sur- 

 rounding water is thus freely admitted. 



Whatever other purposes these cavities may fulfil in 

 the economy of the Medusa, they serve the conveni- 

 ence of another animal of widely different organiza- 

 tion. A little shrimp-like creature, about half-an-inch 

 in length, with large lustrous green eyes (Hyperia 

 mediisarum) , makes these chambers his residence, 

 dwelling in them as in so many spacious and commo- 

 dious apartments, of which he takes possession, I am 

 afraid, without asking leave of the landlord, or paying 

 him even a peppercorn rent. There however, he 



