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that the carcases of whales or other large sea-creatures are 

 soon reduced to skeletons by their aid. Particularly interesting 

 are the Hyperine , to which belongs the Phronima, a little 

 pelagic crab of crystal transparency that , strangly enough , 

 lives in and on the bodies of young Pyrosonia which it eats 

 until they are reduced to mere empty little barrels, and then 

 uses them as moveable habitations. The Phronima fastens itself 

 by its forelegs within this empty barrel, sticks out the hinder 

 part of its body, and using its tail-appendages as oars, swims 

 about, carrying its jelly -barrel with it. This small Diogenes 

 also uses its barrel as a nursery; for not only does it fasten 

 its eggs to the inner walls, but the young ones remain in it 

 for a considerable time even after they have crept out of the 

 eggs. This creature is caught in the surface of the sea in sur- 

 face-nets , together with jelly-fish, Siphonophores, and other 

 representatives of the pelagic jelly animals ; especially in win- 

 ter and spring. 



The Cirripedia are considered to be the lowest order of 

 the Crustacea, and are so unlike the typical form , that it is 

 only quite lately that naturalists have clearly recognized their 

 nature. Even Cuvier thought the hard-shelled Balanus and 

 Lepas were mollusks, until subsequent examination obser- 

 vations on the structure of the young ones and the mi- 

 nute anatomy of the adult proved them to belong to the 

 Crustaceans. How much more difficult must it be for a non- 

 scientific spectator to accustom himself to the idea that these 

 creatures, so unlike in appearance, are indubitable relations 

 of the well known crabs. It may be of assistance to know that 

 their mollusk-like form is the result of a very extensive retro- 

 grade metamorphosis. When young, all these creatures are very 

 lively, freely jumping about in the water. The}?- have a pear- 

 shaped body and three pairs of feet that serve as oars. This 

 form is zoologically called the nawp/tus-form (just as the com- 

 mon larvae of the larger crabs are called zoed). But after several 

 ecdyses they fix themselves by the heads, the skins secrete a 

 covering composed of calcareous plates, which completely hides 

 the crab and permits the feet only to protrude through a gap. 

 The movement of these segmented feet may be beautifully seen 

 in the Balanus as well as in the Lepas. For these animals are 

 continually moving them in order to conduct a current of fresh 

 water to their gills and mouths. On the edge of the rocky coasts 

 of all seas the Balani form a characteristic border , and cling 

 so fast to the stones that the heaviest breakers cannot destroy 



