OP SOUTHEEN INDIA. 8y 



VI. Order,— LUCINACEA. 

 2S,— Family ZJ7CINIJDJE, (sub-fam. conmN^ ^nA. lucinin^J. 



24. „ UNG ULINIBj^: 



25. „ EEYCINIB^. 



26. „ GALEOMMIB^. 



27. „ SOLBMYIDJE, 



28. 55 ASTARTID^^ fsuh-fam. astartinje and cauditinm), 



29. 55 CEASSATBLLIDJE. 



VII. Order,— UNIONACEA. 

 30. — Family TJNIONIDJE, fsub-fam, ujstioninjs and mycetopinjbJ, 



31. 5, MUTFLIDJE. 



32. 5, uFlTSFEIIBJE. 



VIII. Order5— ARCACEA. 

 W>,— Family TEIGONIIB^. 



34. 55 NTICULANIDu^, fsuh-fam, nuculaninm and mallbtinje), 



35. 55 NUCTILIDJE, fsub-fam. nuculinm and saueptinasJ. 



36. 55 AECIJDJE, fsub-fam. axin^in^ and arcing J. 



IX. Order5— MYTILACEA. 

 m.— Family FEASINIBJE. 



38. 5, MYTILIDJE. 



39. 5, FINNIBM. 



40. 55 AVICULIDjF, fsuh-fam. aviculin^, vulsellinje, melininmJ. 



X. Order,— OSTREACEA- 

 41.— Family SPONDTZIJD^. 



42. 55 EADULIBJE: 



43. 5, FFCTINIB^. 



44. 5, OSTEFIBM. 



45. 5, FLACVNIJDJE. 



46. 5, ANOMIIJD^. 



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 siphons5 the second by possessing 

 united siphons covered by an extension of the epidermis of the shell5 but no pro- 

 longed gills. In both these orders the mantle-margins and siphons are united5 and 

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

 entirely separated siphons5 the fourth with short and separated siphons ; 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 



