MALACOZOA. TROPIOFODA. LAMELLIBRANCH1ATA. 205 



pellucid, with numerous radiating costulse and interven- 

 ing strise. Named after Mrs. Loscombe. 



GENUS 3. CRENELLA. Shell free, subelliptical, 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 decussdta. Only one species known. 

 Decussdtus, 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 . Andmia Ephippium. Shell roundish, but variable ; 

 the upper valve little convex, irregularly undulated, 

 sqamoso-lamellate, with the umbo small. Ephippium, 

 a saddle. 



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

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

 Squdmula, a little scale. 



3. Andmia unduldta. Shell roundish, moderately 

 thin ; the upper valve little convex, concentrically rugose, 

 and radiated with irregular undulated ribs. Unduldtus, 

 waved. 



4. An6mia aculedta. Shell roundish, thin, opaque, 

 white ; the upper valve with numerous radiating lamel- 

 loso-spinous ridges ; the umbo glossy and projecting. 

 Aculedtus, prickly. 



5. An6mia punctdta. Shell orbicular, thin, trans- 

 parent ; the upper valve little convex, undulatingly ru- 

 gose, with roundish pustular prominences ; the dorsal 

 outline even or little 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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