282 american journal 



Plate 15. 



16. Colisella pediculus, Phil. Original ; a, uncinus. 



17. " Borneensis, Rve. Original ; a, uncini. 



18. " saccharina, Lin. Original ; a, uncini. 



19. Scurria mesoleuca, Mke. Original ; a, uncinus. 



20. Lottia gigantea, Gray. Original. 



21. Ancistromesus Mexicanus, B. & S. Original. 



22. Patella pentagona. Born. Original. 



23. " vulgata, Lin. Original. 



24. Patinella magellanica, Gmel. Original. 



25. Patinella, sp. indet. Original. 



Plate 16. 



26. Nacella mytilina, Gmelin. 



27. Helcioniscus variegatus, Rve. Original. 



28. " rota, Original. 



29. " exaratus, Rve. Original. 



30. Patina pellucida, Lin, after Loven. 



31. a, muzzle o^ Acma^a ; b, do, of Collisella ; c, do, o^ Patella. 



32. a, profile of teeth of Acmoea ; b, do. of Collisella. 



33. a, jaw of Collisella ; b, do. of Patinella. 



Plate 17. 



34. Collisella syhai'itica, Dall. 



35. " [f patina var.) ochracea, Dall. 



36. " pelta, var. nacelloides, Dall. 



37. " (Collisella ?) Jderoglyphica, Dall. 



38. " Collisella Borneensis, Reeve. 



