171 



1. aperta, Sow. 



2. Australasia?, Gray. 



3. australis, id. 



4. Bakeri, Desk. 



5. Beaniana, Recluz. 



6. branchiata, Gould. 



7. Burmanica, Phil. 



8. calva, Sow. 



9. Campechensis, Gml. 



10. Candida, Linn. 



11. concamerata, Ztes/j. 



12. constructa, Sow;. 



13. costata, Zz?m. 



14. crispata, id. 



15. crucifera, Soic. 



16. Cumingii, ^6?. 



17. cuneiformis, Say. 



18. curta, #0«\ 



Species. 



19. dactylus, Zmre. 



20. Darwinii, Sow. 



21. dorsalis, T«r^. 



22. Erythraea, Gray. 



23. fragilis, Sow. 



24. globosa, zVf. 



25. globosa, Quoy 8f Gaim. 



26. jalan, Ad. 



27. Janellii, Ites/*. 



28. latissima, Sow. 



29. Manillensis, Phil. 



30. melanusa, /Sow. 



31. multistriata, id. 



32. nucifera, 0. Fab. 



33. obtecta, /Sow. 



34. orientalis, Gtnel. 



35. ovoidea, Gould. 



36. ovum, Gray. 



37. papyracea, Sol. 



38. parva, Zwm. 



39. patula, Gould. 



40. pectinata, Cowr. 



41. quadra, Soic. 



42. quadrizonalis, Speng. 



43. rivicola, *Sb?<?. 



44. sunilis, Gray. 



45. spatbulata, /So?/;. 



46. striata, Linn. 



47. subglobosa, Gray. 



48. sulcata, Brown. 



49. tenuis, Gray. 



50. tridens, &>%?. 



51. truncata, Say. 



52. tubifera, Sow. 



Figures. 



Pholas orientalis. P]ate 45. Fig. 243. Shell laid on its ventral edge 

 to show the large accessory shield-like plate which caps the hinge, 

 with a small transverse plate behind it. 



Pholas (Xylophaga) globosa. PL 45. Pig. 241. Shell, showing its 

 small globose form and gaping extremities, the smaller posterior si- 

 phonal aperture being seen through the large anterior pedal aperture. 



Family 13. TUBICOLA. 



Shell ; with or without teeth or ligament, enclosed within a sheath 

 of various dimensions. 



The Tubicola, or tube-inhabiting lamellibranchiates, are so called from 

 dwelling in a tubular sheath in which it is their habit to enclose them- 

 selves. They burrow into sand, wood, coral, or even stone, and accord- 

 ing to the extent of their burrow so the mantle and siphons of the animal 

 become elongated ; and shelly matter is secreted during this elongation of 

 the mantle and siphons independent of the normal bivalve. Owing to the 

 difficulty of obtaining specimens, and of securing the specimens entire, few 

 species are at present known ; but they afford characters of great interest, 



