OP SOUTHERN INDIA. 8y 



VI. Order,— LUCINACEA. 

 23. — Family LJJCINTDJE, fsiib-fam. cobbing and lucinin/e J. 

 21.. „ UNG ULINIBJE. 



25. „ EB YCINIDJE. 



26. „ GALUOinilD^R 



27. „ SOLEMYID^. 



28. „ ASTARTID^, fsnb-fam. astartiNjE and carditin^J. 



29. „ CBASSATELLIBjE. 



VII. Order,— UNIONACEA. 

 30. — 'Family TJNIONIDM, (suh-fam. unionism and uycetopinm). 



31. „ MUTELIB^. 



32. „ ^TEEBIID^. 



VIII. Order,— ARCACEA. 

 33.— i^«Hi% TBIGONIID^. 



34. „ NUCULANIDuE, (suh-fam. nuculaninm and jialletin^J . 



35. „ NUCULIDJE, f suh-fam. nuculinm and sareptinmJ. 



36. „ ABCIDJEJ, (suh-fam. axinminm and arcing J. 



IX. Order,— MYTILACEA. 

 SI.— Family PBASINIDJE. 



38. „ 3IYTILID.F. 



39. „ FINNIBJE. 



40. „ AVIQTJLIDJE, (suh-fam. avicvlinm, vulsellin^, melininmJ. 



X. Order,— OSTREACEA. 

 '^1.— Family SFONDYLID^. 



42. „ i?^i) ULID^. 



43. „ FECTINIDJE. 



44. „ OSTBEIBuF. 



45. „ FLACUNID^. 



46. „ ANOMIID^. 



Taking a very general view of these orders the following summary may be 

 interesting in point of comparison. The animals of the first order are chiefly dis- 

 tinguished by having the gills prolonged into the siphons, the second by possessing 

 united siphons covered by an extension of the ej^idermis of the shell, but no pro- 

 longed gills. In both these orders the mantle-margins and siphons are united, and 

 the latter equally prolonged. The third order represents the type with long but 

 entirely separated siphons, the fourth with short and separated sii)hons ; both have 

 the mantle-margins widely open in front. The fifth order appears to be an aber- 

 rant type of the second, having the mantle- margins united, but possessing the 

 short siphons of the fourth order, and a habitat which corresponds with the 



