288 WORMS. TESTACEA. 68. Mytilus. 



Inhabits m found adhering to the Madrepore prolifera - 



Jhell dirty ochre; with a large perforation at the tip, Joneer 

 on gnQ fide, r 5 



QryphoUes Shell oval, fmooth, folic!, opake; the letter valve with a 

 ftraightifh obtufe truncate beak. 



Inhabits Schr/et. Joum* 4. tab. 2, Jig. 8. 



Shell whitifh: refemblee A. Gryphus. 



Fkxuofa. Shell very thin,- lamellate, hollowed in the middle: the 



upper-valve flat ; lower-valve convex towards the 



crown; with an orbicular perforation beneath the 



crbvvn. 



Inhabits Norway f e a$, adhering to the Madrepore prolifera : ; 



Jhell fmoke-colour, the convex part of the lower-valve filveiy. 



9*$m Shell' obovate ; the upper valve convex for the greater part, 

 and very finely wrinkled; lower-valve very thin and 

 fmboth with a kidney-fhaped perforation. 

 Schrcct. Einl. in conch. 3. tab. 9. fig, jz 4 

 Inhabits Norway feas, fixed to the Madrepora prolifera. 

 Shell vvhitiih, with a very acute margin. 



Cylmdrica. Shell very thin, cylindrical am* narrowed outwardly • up* 

 per-valve gibbous, lower hollow. ' 



Schrat. Einl. in conch. 3. tab. 9. Jig. 13, 

 Inhabits North fem x adhering to the*fpines of the Echinus Cidaris, 



Nucleus. Shell glabrous, oval and longitudinally grooved. 

 . . Inhabits North feas. Mull. Z00L Dan. prodr. 3008. 



Avenacea. Shell pyriform, pfotratfed and flightly compreffed towards 

 the hinges. 

 Inhabits North/eat. Mull. Zoo/. Dan. pro Jr. 3004. 



Sandalium. Shell turbinate, the back flat, with a folate cavitv • the 



lid flat and hemifphasrical. 



Inhabits i Germany, in a foffile Hate : in figure fomething refembles 



the Madrepora turbinata: Jkdi Colid, thick, about the fize of 



a man s little finger : the Kd or flat valve concentrically flriate. 



68. MYTILUS. Animal allied to an Afcidia: 



Jhell bivalve, rough, generally affixed by 



a byffus or beard of filky filaments; hinge 



mofily without teeth, with generally a 



fubulate excavated longitudinal line. 



