MALACOZOA. TROPIOFODA. LAMELLIBRANCHIATA. 205 



pellucid, with numerous radiating costulse and interven- 

 ing striae. Named after Mrs. Loscombe. 



Genus 3. Crenella. — Shell free, subelliptieal, equi- 

 valve, isomeral, convex, pearly ; the hinge with a single 

 abrupt fold in each valve ; the ligament external, in a 

 narrow groove, under the umbones, which are prominent 

 and contiguous ; the valves radiatingly striate, and con- 

 centrically striulate. Named by Capt. Brown apparently 

 from its crenulate appearance. 



1. Crenella decussata. — Only one species known. 

 Becussdtus, marked with lines crossing each other. 



Genus 4. Anomia. — Shell adherent, irregular, inequi- 

 valve, delicate, fragile ; the lower valve flat, with an 

 aperture or notch near the hinge, for the attachment of 

 the animal to some hard substance. Linnaeus. 



1 . Anomia Eph'ippium. — Shell roundish, but variable ; 

 the upper valve little convex, irregularly undulated, 

 sqamoso-lamellate, with the umbc small. Ephippiumy 

 a saddle. 



2. Anomia Squdmula. — Shell roundish, very thin ; the 

 upper valve little convex, smooth, with the umbo small. 

 Squdmula, a little scale. 



3. Anomia undulata. — Shell roundish, moderately 

 thin ; the upper valve little convex, concentrically rugose, 

 and radiated with irregular undulated ribs. JJndiddtuSj 

 waved. 



4. Anomia acidedta. — Shell roundish, thin, opaque, 

 white ; the upper valve with numerous radiating lamel- 

 loso-spinous ridges ; the umbo glossy and projecting. 

 Acidedtus, prickly. 



5. Andmia punctata. — Shell orbicular, thin, trans- 

 parent ; the upper valve Uttle convex, undulatingly ru- 

 gose, with roundish pustular prominences ; the dorsal 

 outline even or Httle rounded. Punctdtus, covered with 

 raised dots. 



6. Anomia cylindrica. — Shell subovate, thin, subpel- 

 lucid ; the upper valve very convex, squamoso-rugose, 



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