352 THE INHABITANTS OF THE SEA. 



Though generally preferring to lie at anchor, the Lucer- 

 narioe are able to detach themselves, and to swim in an 



inverted position by the 

 slowly repeated movements 

 of their cup-like umbrella. 

 When in a state of expan- 

 sion, few marine creatures 

 exceed them in beauty and 

 singularity of form ; when 

 Lucemaiia auricula. contracted, they are shape- 



(Natural size.) . 



less, and easily overlooked. 

 " Their mode of progression," says Mr. Couch, " differs under 

 different circumstances. If intending to move to any great 

 distance, they do so by loosening their attachments, and then, by 

 various and active contortions, they waft themselves away till they 

 meet with any obstruction, where they rest; and if the situation 

 suits them, they fix themselves; if not, they move on in the 

 same manner to some other spot. If the change be only for a 

 short distance, as from one part of a leaf to another, they bend 

 their campanulate rims, and bring the tentacula in contact with 

 the jaws, and by them adhere to it. The foot-stalk is then 

 loosened and thrown forward and twirled about till it meets 

 with a place to suit it ; it is then fixed, and the tentacula are 

 loosened, and in this way they move from one spot to another. 

 Sometimes they advance like the Actiniae, by a gliding motion 

 of the stalk. In taking their prey, they remain fixed with their 

 tentacula expanded, and if any minute substance comes in con- 

 tact with any of the tufts, that tuft contracts, and is turned to 

 the mouth, while the others remain expanded watching for prey." 

 The Calycoph oriel 33 are distinguished by the cup-shaped 

 swimming organs, which form the most prominent part of their 

 body. Generally transparent like glass, their course upon 

 distant inspection is only revealed by the bright tints of 

 some of their appendages. In Diphyes, the type of the group, 

 the two cups {y, v") fit into each other so as to form a 

 more or less perfect close canal. The common stem of the 

 numerous polyp colony freely glides up and down the chamber 

 thus formed, into which it can be completely retracted, and 

 along its sides are placed the several appendages of the compound 

 creature, consisting chiefly of polypites (77-), tentacles, and 



