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times with a small lengthened fissure in the centre"; 

 it has a waved testaceous subtubular fringed border 

 projecting beyond the perifery of the outer circle. On 

 the side of the tube, near its extremity, are two per- 

 manently fixed valves, leaving an open fissure between 

 them : the exterior of the tube of some species is in- 

 crusted with sand. 



La Marck considers this shell an equivalve bivalve 

 allied to the genus Fistulana, in which, however, the shell 

 it incloses is detached and free, while in the Aspergillum 

 it adheres to the sheath, completing, by the two fixed 

 open valves, a part of the tube that incloses the animal. 

 He remarks, that it is no doubt an error to suppose that 

 this shell is ever fixed by the open end, which, like 

 the Clavagella, and Fistulana, must necessarily be open 

 for the egress of the animal. He describes four spe- 

 cies. It is known to conchologists in England by the 

 familiar name of the Watering-pot shell. 



A fifth, and most extraordinary species, was disco- 

 vered and brought to England by the Earl of Mountnor- 

 ris. The tube is of a considerable circumference, almost 

 straight, and nearly of an uniform size during its whole 

 length, which sometimes reaches upwards of twelve 



