xxvL CO^CRYLIA—DITHYRA. 



2. elliptica, lateribus rotundatis. 



rounded at both ends. 



23. Mactra. 



* dentihus lateralibus striatis. 

 the lateral teeth striate. 



1. solida, ovato-trigona, cequilateralis, loeviuscula. 



oval-triangular, equilateral, and smooth. 



2. truncata, trigona, (equilateralis , lateribus truncatis. 



triangular, epuilateral, truncate at the sides. 



3. crassa, trigona, in(equilateralis Iceviuscula. 



triangular, inequilateral, nearly smooth. 



4. suhtruncata, ovato-trigona, intequilateralis, transversim sulcata. 



oval-triangular, inequilateral, grooved trans- 

 versely. 



5. deaurata, oblonga, inaquilateralis, transversim rugosa. 



oblong, inequilateral, transversely wrinkled. 

 ** dentibus lateralibus leevibus. 

 with the lateral teeth smooth. 



6. Stultorum, equilateralis, transversi)n substriata. 



equilateral, and slightly striate transversely. 



7. cini'rea, subeequilateralis, IcBviuscula. 



nearly equilateral and smooth. 



8. glauca, inoequilateralis, transversim striata. 



inequilateral and striate transversely. 



