183 



cess affixed to a central septum ; in T. crenulata (Mat/as, Sowerby) there 

 is a central septum with two pairs of lamellae; in T. tulipa (Bouc/iardia, 

 Davidson) the shell has only a minute foramen for the pedicle and the 

 apophysis is anchor-shaped ; in T. truncata {Mergerlia, King) two short 

 diverging branches arise from the extremity of the septum ; in T. Capensis 

 {Kraussia, Davidson) the apophysis consists of a small forked process 

 arising from the septum ; in T. Anomioides {Morrisia, Davidson) a minute 

 form, two branches arise from the centre of the valve and they are not re- 

 flected ; in T. cistellula (Argiope, Deslongchamps), another minute form, 

 the apophysis is represented by one or more internal ribs ; and, lastly, in 

 T. Mediterranea {Thecidiuw, Defrance) the loop is folded into two or more 

 lobes resting in corresponding hollows of the upper valve. With these 

 modifications of the apophysary system there are also other general mo- 

 difications of the shell and of the animal, of which the importance will, 

 doubtless, increase as more observations are made, and they are better 

 understood. 



1. abyssicola, Ad. $• Rv. 



2. angusta, id. 



3. Anomioides, Scac. 



4. Bouchardii, Bav. 



5. Californica, Koch. 



6. cancellata, id. 



7. Capensis, Ad. $* Rv. 



8. caput-serpentis, Linn. 



9. caurina, Gould. 



10. Chilensis, Brod. 



11. cistellula, Wood. 



12. cognata, Chemn. 



13. Coreanica, Ad. fy Rv. 



14. cranium, Mull. 



15. crenulata, Sow. 



16. cruenta, Bill. 



17. Cumin gii, Bav. 



18. Cumingii {Mag.), B. 



Species. 



19. cuneata, Riss. 



20. decollata, Gmel. 



21. dilatata, Lam. 



22. dorsata, Gmel. 



23. Evansii, Bav. 



24. flavescens, Lam. 



25. globosa, id. 



26. Grayi, Bav. 



27. Japonica, Sow. 



28. flexuosa, King. 



29. frontalis, Midd. 



30. Labradorensis, Sow. 



31. Lamarckiana, Bav. 



32. lenticular! s, Desk. 



33. lunifera, Phil. 



34. Mediterranea, Riss. 



35. Neapolitana, Scac. 



36. Patagonica, Gould. 



37. picta, Cltemn. 



38. pisum, Lam. 



39. pulchella, Sow. 



40. pulvinata, Gould. 



41. rubella, Sow. 



42. rubicunda, id. 



43. rubra, Pall. 



44. sanguinea, Chemn. 



45. septentrionalis, Couth. 



46. septigera, Loven. 



47. Sowerbyi, King. 



48. Spitzbergensis, Bav. 



49. transversa, Sow. 



50. truncata, I Ann. 



51. tulipa, Blainv. 



52. uva, Brod. 



53. Valencienni, Bav. 



54. vitrea, Linn. 



Figures. 



Terebratula caput-serpentis. PI. P. Fig. 1. Shell, showing the na- 

 tural position of the mollusk, affixed by a tendinous pedicle lowered 

 from the beaked projection of the upper valve. 



