344 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



24. Chiton SU)kesii Brod., Peru: a, major uncinus from below. 



25. Chiton Cinningn Frembly, Chili. 



26. Chiton assimilis Reeve, West Indies. 



27. Tonieia elcgans Frembly, Cbili. 



28. AcanthopUura sjnnigera Sby., Aden. 



29. Lucia confossa Gld., Patagouia: a, minor lateral ; h, major uncinus. 



30. Corcphium ecMnalum Sby., South America. 



Plate IV. 



31. Nuttallina scdbra Reeve, California. 



32. PhaceUopleura porphjritica Reeve. 



33. Placiphora CarmichacUs Gray, South America. 



34. Mopalia WossnesscnsMi Midd., Alaska. 



35. Mopalia ciliafa Sby., Alaska: a, minor lateral. 



36. Placiphorella velata Cpr., California: a, minor lateral from inner side. 



37. Eathcrina tunicata Wood, Alaska. 



38. Acanthochiton avicula Cpr., California. 



39. Acantltochiion spiculosus Rve., West Indies. 



40. Macandrellus {costatus ? Ad. & Angas), Australia. 



Plate V. 



41. Cryptoconchus monticularis Quoy, New Zealand. 



42. Amicula Pallasii Midd., Alaska. 



4.3. Amicula resfita Sowerby, Massachusetts Bay. {Emcrsonii Couth.) 



44. Cryptochiton Sielleri Midd., Alaska. 



45. ChitoneUus fasnatns Quoy, Caspar Straits: a, minor lateral from outer side. 



46. Viewof the anterior end of a Chiton from below: a, muzzle; 6, veil; c, fringe or truo 



mantle-edge; d, lower surface of girdle; e, end of row of "ambient" branchiae; 

 /, lower surface of foot. 



47. Developement of larval Chiton, Trachydermon cinereus Lowe (T. marginatus JeiFreys), 



after Lov^n: a, cml)ryo, in the egg; h, dorsal view of larva, showing the com- 

 mencement of the grooves for the valves ; c, lateral view of the same ; d, larva 

 further advanced, the valves beginning to be formed; e, the same, from beneath, 

 showing the foot and eyes at the sides of the head ; /, dorsal view of an older 

 individual, showing the diminished size of the anterior tuberculate lobe or head. 



Note. — The figures of dentition are diagrams, not portraits, designed 

 to indicate the form of the individual teeth rather than the superficial 

 appearance of the undisturbed radula. While the photographic relief 

 process, by which tliese plates were obtained ti-om the original drawings, 

 has not been as satisfactory in its results as was at first hoped, it is be- 

 lieved that, inartistic as they may appear, the figures are more charac- 

 teristic than if they had been redrawn and subjected to the artistic 

 modifications of a professional draughtsman unacquainted with the sub- 

 ject. 



