231 



4. p. 565. t. 15. .f5.F.p. 234.Macff. Ab.p. 37. 

 SERPULA O. Walk. t. I./. 4. Turt. D.p. 155. 

 Oblong, oval, opaque, glossy white, somewhat com- 

 pressed ; on one side a single longitudinal suture which 

 seems to divide the shell into two parts; on the other 

 side the middle compartment is surrounded by a faint 

 depression, that separates it from the exterior one, and 

 is more elevated ; aperture a little produced, oval, the 

 margin yellow. 0,04... In sand from Sulcomb Bay, 

 Devon, rare. 



V. DISCIFORME. Macg. Aberd. p. 319. Orbi- 

 cular, very thin, of four arcuated flattened turns, which 

 are opaque, greyish or reddish white, moderately glossy, 

 faintly rugose, striated longitudinally the outer margined 

 with a bluish white keel ; on one side all the four turns 

 apparent, on the other, three ; aperture large, direct, 

 oblong or even linear ; margin parallel, rim thickish 

 and generally reddish brown, a medial erect tooth ex- 

 tending to more than half the height of the mouth. 

 0,08... Aberdeen. Differs from Intortum in its orbi- 

 cularity, its lesser thickness, its thinner keel and 

 much narrower mouth. 



V. PLANATUM. Macg. Aberd. p. 319. Roundish , 

 very thin, of three arcuated, much compressed, yellowish 



