95 



Compared with the Arks the Pectunculi have a rounder lens-shaped 

 shell, with the hinge teeth set in a curve. The shell is moreover charac- 

 terized by a richer display of colour, varying from a dark brown to a rich 

 purple and rose, and even brilliant orange ; and the ligament area between 

 the umboes is narrower and more deeply excavated. The animal exhibits 

 strongly the peculiarity noticed in this and the preceding family of the foot 

 being crimped round the edge, and it has no byssus. 



The genus is very widely distributed, chiefly about Central America and 

 the AVest Indies. There is only one British species. 



1. angulatus, Lam. 



2. assimilis, Sow. 



3. aurifluus, Reeve. 



4. bicolor, id. 



5. cancellatus, id. 



6. castaneus, Lam, • 



7. Delessertii, Reeve. 



8. flammeus, id. 



9. fonnosus, id. 



10. giganteus, id. 



11. glycimeris, Turton. 



12. holosericus, Reeve. 



13. inaequalis, Sow. 



14. intermedins, Brod. 



15. latieostatus, Quoy. 



16. lineatus, Reeve. 



17. longior, Sow. 

 IS. rnaculatus, Brod. 



Species. 



19. marmoratns, Cliemn. 



20. morum, Reeve. 



21. inulticostatus, Sow. 



22. multistriatus, Desk. 



23. nodosus, Reeve. 



24. obliquus, id. 



25. oculatus, id. 



26. o vat us, Brod. 



27. pallium, Reeve. 



28. parcipictus, id. 



29. Pectenoides, Desk. 



30. pectinatus, Lam. 



31. Pectiniformis, id. 



32. pennaceus, id. 



33. perdix, Reeve. 



34. pertusus, id. 



35. pilosus, Lam. 



36. radians, id. 



37. roseus, Reeve. 



38. rubeus, Lam. 



39. scriptus, id. 



40. sericatus, Reeve. 



41. Siculus, id. 



42. spadiceus, id. 



43. spurcus, id. 

 ,44. stella tus, Lam. 



45. striatnlaris, id. 



46. strigilatus, Soto. 



47. Tellinseformis, Reeve. 



48. tenuicostatus, id. 



49. tessellatus, Sow. 



50. undulatus, Lam. 



51. violaseens, id. 



52. vitreus, id. 



Figure. 



Pectunculus aurifluus. PL 34. Fig. 185. Shell, showing its rounded 

 form and variegated colour, with the teeth set in a curve. 



Genus 4. NUCULA, Lamarck. 



Animal ; snbtrigonal, its mantle freely open, icitlt or without si- 

 phonal tubes and with plain edges ; foot deeply grooved and 

 forming an ovate pedunculated disk, with a serrated edge. 



