CONCHIFERA. 



291 



thicks very brilliant inside, and of a red cast ; it is coated 

 with a thick, dark, olive-green epidermis, under which the 

 shell is white, but dull. Caillaud says that the natives of 

 Egypt use the valves in preparing flax, and as spoons in 

 measuring oil, butter, and different kinds of provisions. 



Mycetopus. D* Orb. — Shell thin, transverse, equi- 

 valve, nearly equilateral, of a ^^^na^i^a^^^ 



long cylindrical form, gaping 

 at both ends, more particularly 



at the anterior; covered with Mycetopus sdlenoides . 



a dark olivaceous epidermis, 



somewhat rubbed off towards the umbones, and the in- 

 terior is lined with a slight nacre ; the umbones are central, 

 and turned directly inwards to each other ; the hinge is 

 linear, straight, and without teeth, furnished with a thin 

 marginal ligament ; the muscular points of attachment are 

 rather indistinct, being but faintly impressed, the anterior 

 one is compound.* Animal having the mantle cloven its 

 whole length, without projecting siphons, but with a sepa- 

 rate anal opening; foot very long, and cylindrical, pro- 

 jecting out at the point, which cannot be bent back into 

 the shell ; a large mouth opening, lengthened tentacles, 

 and very large gills. — 2 species. 



M. (Anodon) siliquosus, of Spix, and M. soleniformis, 

 of D'Orbigny, are found in the rivers of South America. 



Family 20. — JE THERIA CEA. 



The animal has both the mantle lobes separated ; on each 

 side two dissimilar, striped, leaf-shaped gills, which under 

 the end of the foot are connected together, so that they 



* Reeve's Conch. Syst. 



