PART II. ATRACHIA. HYRIAN^. 379 



dinal teeth compressed and crenated ; the outer sharp^ 

 and almost parallel with the anterior margin. 

 M. pictorum* Linn. En. Batava Za?H. En. Meth. 248. 

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



ovata Sic. {fig. 56.) marginalis. lb. 247. f. 1. 



Potomida Sw. Oval ; cardinal teeth shorty thick, the 

 outer one diverging towards the anterior margin. 

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



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



Lymnadea Sw. Posterior hinge margin elevated and 

 winged ; the valves connate ; the surface smt)0th. 

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

 (/^. 48.) p].12. f. 22. 



fragilis Sw. Zool. 111. 



SuB-FAM. 2. HYRIANiE. 



Bosses longitudinally sulcated ; cardinal teeth long, com- 

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

 winged, {fig. 123. g.) 



Iridea Sw. Oblong ovate ; bosses small, depressed, 

 sulcated ; inner cardinal tooth placed beneath the 

 outer. 



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



Castalia Lam. Oval or trigonal, nearly equilateral ; 

 bosses prominent ; cardinal teeth short, thick ; the 

 outer largest and crested. 



JVa'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 | 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 Ovata, as Lamarck has done. 

 ^ t This is not a typical species, but it is the only one, out of ten or twelve, 

 ' which I believe is figured. 



t Castalia nmbigua Lam. A name quite inadmissible to a decided 

 species ; it is the Cordata of Humphrey, 



