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them. They bear equally well being left dry during ebb-tide, 

 the small quantity of water they retain within their hermeti- 

 cally closed valves enabling them to resist the greatest heat of 

 the sun. Many kinds are found settled on whales in heaps. 



The Lepas settle by preference on floatings bodies, ships , 

 pieces of wood , and similar things being covered by them. 

 Their name is derived from the fable that out of them is de- 

 veloped the barnacle-goose (1). 



The Scalpellum vulgare also belongs to the Lepadidae. It 

 is a deep-sea animal remarkable for its sexual condition. These 

 animals are hermaphrodite, but as if to secure the preservation 

 of the species, they carry, in a special bag or pocket, several 

 dwarf or complementary males of infinitesimal size ! 



The most remarkable thing in retrograde metamorphosis is af- 

 forded by the parasites known as root-crabs , which live on the 

 hind parts of prawns and hermit-crabs. They are nothing but un- 

 shapely sacks filled with eggs and connected with the bodies of 

 their victims by a short stem and a bunch of branching sucking 

 tubes, through which the animal juices are drawn. The nature 

 of such forms which parasitism has caused to degenerate until 

 they have lost all resemblance to crabs, could only be deter- 

 mined by naturalists by the study of their development ; and 

 indeed the problem was only solved when the nauplius-larvae 

 were discovered. 



Ilollusca. 



The highest developed class of Mollusks is that of the Ce- 

 phalopods , distinguished by a head separated from the body, 

 and a mouth- orifice surrounded by prehensile arms. The Aqua- 

 rium contains the following kinds: 



The Eight- armed sea-poulp or octopus (Octopus vulgaris), 

 frequently found on the rocky coasts of the Mediterranean. This 

 creature has a body like a bag, which we see breathing with 

 a rythmic motion; this is the body proper of the animal and 

 contains the intestines. The small head at the top contains the 

 two large eyes, and from it proceed eight arms covered on 

 the under-side with sucking-disks. The mouth lies in the cen- 



(1) This myth, which can be traced back to the 12th century, probably owed 

 its orio-m to the monks of that period , who wished to add something to 

 the scanty fare allowed during last. At least according to credible wit- 

 nesses , it was affirmed by Irish and French bishops that barnacle-geese 

 xvere produce of the sea, and therefore no flesh. 



