CONCHIFERA OR BIVALVES. 55 



This very curious shell derives 

 its name from its form, and varies 

 in length from seven or eight 

 inches to a foot ; it is supposed 

 by some authors that it attaches 

 itself to the rocks by a byssus 

 passing through the holes in the 

 plate which terminates its tube, 

 but it has generally been found 

 on the sand : its colour is white, 

 with a slight tinge of grey or 

 pale red. 



The Aspergillum agglutinans, 

 from New Holland, has the disk 

 or plate differently constituted 

 from the other species : instead 

 of the small holes are substituted 

 slender tubes, separate and un- 

 equal, with a fissure in the centre. 

 Its specific name is derived from the circum- 

 stance of the tube being constantly covered 

 with sand, fragments of shells, and madrepores. 

 The Aspergillum Javanum, from New Zealand 

 and Java, is the most common species. 



" The row of slender tubes round the disk 

 E 4 



