PART II. ATRACHIA. — HYRIAN^. 379 



dinal teeth compressed and crenated; the outer sharp^ 

 and almost parallel with the anterior margin. 

 M. pictorum * LinJi. En. Batava Larn. En, Meth. 248. 

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



ovata SiL\ {Jig. 56.) ' '" marginalis, lb. 247. f. 1. 



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



outer one diverging towards the anterior margin. 



P. sinuata Za?w, 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 smooth. 



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

 {fig. 48.) pi. 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 bosses ; hinge margin 

 winged, {^fig. 123. g.) 



Iridea Siv. Oblong ovate ; bosses small, depressed, 

 sulcated ; inner cardinal tooth placed beneath the 

 outer. 



I. granosa Lmji. En. Meth. 248. f. 9.t 



Castalia Lam. Oval or trigonal, nearly equilateral ; 

 bosses prominent ; cardinal teeth short, thick ; the 

 outer largest and crested. 



Naia 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 SpLv. 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. 



f This is not a typical species, but it is the only one, out of tenor twelve, 

 which I believe is figured. 



J Castalia amhigua Lam. A name quite inadmissible to a decided 

 species ; it is the Cordata of Humphrey, 



