288 WORMS. TESTACEA. 68. Mytilus. 
Inhabits—- found adhering to the Madrepora proHff'*' 
Jhell dirty ochre; with a large perforation at the tip, 
on one fide. ^ 
GryphoUes Shell oval, fmooth, folid, opake; the lefler valve ^ 
ftraightilh obtufe truncate beak. 
Inhabits Schriet, Journy 4. tab. 2, fig. 8. 
Shell whitilh : refembles A. Gryphus. 
Flexuo/a. Shell very thin, lamellate, hollowed in the middle; 
upper-valve flat; lower-valve convex towards 
crown, with an orbicular perforation beneath 
crown. 
Inhabits Nornuay feas, adhering to the Madrepora prolif**^/ 
Jhell fmoke-colour, the convex part of the lower- valve fib'®'! ' 
Rugo/a. Shell obovate ; the upper valve convex for the greater 
and very finely wrinkled; lower-valve very thin 3 '''“ 
fmooth with a kidney-fhaped perforation. 
Schrxt. Etnl. in conch. 3. tab. fig. 12. 
Inhabits Norway feas, fixed to the Madrepora prolifera. 
Shell whitilh, with a very acute margin, 
Cylindrica. Shell very thin, cylindrical and narrowed outwardly; “P' 
per-valve gibbous, lower hollow. 
Schrtet. Einl. in conch. 3. tab. c^. fig. ij. 
Inhabits North feas, adhering to the fpines of the Echinus Cida'''*'’ 
Nucleus. Shell glabrous, oval and longitudinally grooved. 
Inhabits Mull. Zool. Dan, prodr, 3008. 
Avcnacea. Shell pyriform, protraded and flightly comprefled toward* 
the hinges. ^ 
Inhabits North fias. MuU. Zool. Dan. prodr. 3004, 
Sandalium. Shell turbinate, the back flat, with a ftriate cavity ; 
lid flat and hemifphaerical. 
Inhabits Germany, in a foffilc ftate ; in figure fomething refembi'l j 
the Madrepora turbinata: fhell iaXxdt, thick, about the fia* ° ' 
a man s little finger : the lid or flat valve concentrically 
()8. MYTILUS. Animal allied to an 
Jhell bivalve, rough, generally affixed W 
a byffiis or beard'oflilky filaments: 
inofily without teeth, with general!/ 
fubulate excavated longitudinal line. . < 
