UNIVALVES SERPU LA . 1 1 7 



the fojlowino : viz, Serpula protensa, and Serpula poly- 

 thalamia. The latter of which most probably belongs 

 to the ^enus teredo; it is remarkable for having its 

 interior separated by imperforate, convex, and concave 

 divisions, making the shell appear as if it consisted of nu- 

 merous united tubes. The smaller end of this shell is also 

 peculiar for being terminated by two distinct or separate 

 small tubular pipes, which are jointed in the same man- 

 ner as the main stem from which they spring; the shell, 

 in this state, looks something like a two-pronged fork. 

 It is an inhabitant of the Mediterranean and Indian seas, 

 and is often found concealed under the sands : it some- 

 times arrives at the extraordinary size of three feet. 



To this same division belongs the well known but rare 

 shell, the watering-pot Serpula. The larger end of this 

 shell is closed by a convex disk, which is beset with nu- 

 merous small perforations, and a longitudinal one in the 

 middle, the whole encircled by a dilated margin of ele- 

 gant papyraceous tubes, exactly resembling a beautifully 

 plaited ruff or frill ; the smaller end is open. In point of 

 size, it seldom exceeds five inches. The Indian ocean is 

 its birth place, and, when perfect, it is highly valued. 



The Serpula gigantea sometimes grows to half-a-foot 

 high, and about the thickness of a finger. The Serpul^^ 

 lumbricalis, or cork-screw shell, is flexuous, and has a 

 spiral acute tip, very much resembling the article after 

 which it is named. The Serpula filograna is branched 

 and complicate, and is adorned with a beautiful kind of 

 net work. 



One of the remarkable species of this genus is the Ser- 

 pula anguina, which has a split or long-jointed cleft, all 

 along the spiral convolutions of its shell. The Serpula 

 echiuata has its shell beset with a succession of spines or 

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