344 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



24. Chiton Slokesii Brod., Peru: a, major unciims from below. 



25. Chiton Cumingii Frembly, Chili. 



26. Chiton assimilis Reeve, "West Indies. 



27. Tonicia elegans Frembly, Chili. 



28. Acanthopleura spinigera Sby., Aden. 



29. Lucia confossa Gld., Patagonia: a, minor lateral ; b, major uncinus. 



30. Corephium echinaium Sby., South America. 



Plate IV. 



31. Nuttallina scdbra Reeve, California. 



32. Phacellopleura porphyritica Reeve. 



33. Placiphora Carmichaelis Gray, South America. 



34. Mopalia Wossnessenskii Midd., Alaska. 



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



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



37. Katheiina tunicaia Wood, Alaska. 



38. Acanthochiton avicula Cpr., California. 



39. Acanthochiton spiculosus Rve., West Indies. 



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



Plate V. 



41. Cryptoconchus monticularis Quoy, New Zealand. 



42. Amicula Pallasii Midd., Alaska. 



43. Amicu la vestita Sow erby, Massachusetts Bay. (Emersonii Couth.) 



44. Cryptochilon Stelleri Midd., Alaska. 



45. Chitonellus fasciatus Qnoy, Gaspar Straits: a, minor lateral from outer side. 



46. View of the anterior end of a Chiton from below : a, muzzle ; b, veil ; c, fringe or true 



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

 /, lower surface of foot. 



47. Developement of larval Chiton, Trachydermon cincreus Lowe ( T. marginatus Jeffreys), 



after Lov6n: a, embryo, in the egg; b, 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 tuberculato lobe or head. 



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

 to indicate the form of the indii idual teeth rather than the superficial 

 appearance of the undisturbed radula. While the photographic relit if 

 process, by which these plates were obtained from 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. 



