PART II. ATRACHIA. HYBIAN-ffi. 379 



dinal teeth compressed and crenated; the outer sharp, 



and almost parallel with the anterior margin. 



M. pictorum * Linn. En. Batava Lam. En. Meth. 248. 



Meth. 248. f. 4. f. 3. 



ovata Sw. (fig. 56.) marginalis. Ib. 247. f. 1- 



Potomida Sw. Oval; cardinal teeth short, thick, the 

 outer one diverging towards the anterior margin. 

 P. sinuata Lam. En. Meth. corrugata Sw. (fig. 51.) 



pi. 248. f. a, b. littoralis. En. M. 248. f. 2. 



Lymnadea Sw. Posterior hinge margin elevated and 

 winged ; the valves connate ; the surface smooth. 

 L. alata Sw. Ex. Conch. ? compressa Lea. Am. Tr. iii. 



(fig. 48.) pi. 12. f. 22. 



fragilis Sw. Zool. 111. 



SUB-FAM. 2. HYRIAN^E. 



Bosses longitudinally sulcated ; cardinal teeth long, com- 

 pressed, placed on one side of the hosses ; hinge margin 

 winged, (fig. 123. g.) 



IUIDEA Sw. Oblong ovate ; bosses small, depressed, 

 sulcated ; inner cardinal tooth placed beneath the 

 outer. 



I. granosa Lam. En. Meth. 248. f. 9.f 



CASTALIA Lam. Oval or trigonal, nearly equilateral ; 

 bosses prominent ; cardinal teeth short, thick ; the 

 outer largest and crested. 



Na'ia Sw. Oval ; cardinal teeth beneath the bosses, 

 and deeply sulcated. 



C. corrugata Lam. En. picta Sw. En. Meth. 248. 



Meth. 248. f. 8. f. 6. 



Castalia Lam. Trigonal, nearly heart-shaped. 



C. cordata J Sw. Sow. Man. pectinata Spix. Braz. Test, 

 f. 140. pi. 25. f. 3, 4. 



* And of all the British writers who have not confounded it with the 

 British Grata, as Lamarck has done. 



f This is not a typical species, but it is the only one, out often or twelve, 

 which I believe is figured. 



J Castalia ambigua, Lam. A name quite inadmissible to a decided 

 species ; it is the Cordata of Humphrey, 



