296 



POPULAR CONCHOLOGY. 



not united to form a siphon, constitute pouting, and more 

 or less puckered branchial lips; formed into a true and 

 produced tube anally ; adductor muscles unequal ; foot 

 narrow, ligulate, furnished with a byssal groove.* — Several 

 species ; also fossil. 



Elegant little shells, usually boring into the skins of 

 tunicated Mollusca ; they are found in the European 

 seas, and about six on the English shores; the author 

 has received several fine specimens from New Zealand, 

 seemingly identical with the English species C. marmorata. 



Lithophagus. Megerle von Muehlfdd. (Lithodomus, 

 Cuv.) — Shell transverse, 

 cylindrically oblong, equi- 

 valve, and covered with a 

 brown epidermis ; extremi- 

 ties round; bosses scarce- 

 ly prominent ; the hinge mhopnagus daayius. 

 straight; ligament mostly 



internal. Animal, not differing materially from Mytilus, 

 but in maturity, it has no byssus. — About 12 species; 

 also fossil. 



The Lithophagus, when young, suspends itself to rocks 

 by a byssus f, but, as it grows, it pierces a hole, and in- 

 troduces itself, forming a cavity which thenceforward it 

 never leaves : indeed, after a short time, as it merely 

 enlarges the interior, without making the entrance any 

 wider, its increasing bulk renders it unable to quit its 

 cell, and in these circumstances its byssus, being no longer 

 necessary, dies away. It is common in the Mediterranean 

 and the Antilles, where it often pierces other shells. 



Dkeyssena. Van Beneden. (Tichogonia Bossm. ; Con- 



* Forbes' s British Moll. 



f This assertion is from Cuvier ; Sowerby thinks it has no byssus. 



