344 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



24. Chiton Siokcdi Brod., Foni: a, major uncinus from below. 



25. Chiton Cumingii Frembly, Chili. 



26. Chiton assimilis Reeve, West Indies. 



27. Tonicia de(jans Frembly, Chili. 



28. Acantho2)leura spinigera Shy., Aden. 



29. Lucia covfoam GUI., Patagouia: a, minor lateral; h, major uncinuB. 



30. Corephium echinatum Sby., South America. 



Plate IV. 



31. NuttalUna scabra Eeeve, CaUibrnia. 



32. Phacellopleura porplujritica Reeve. 



33. Pladphora Carmichaelis Gray, South America. 



34. Alopalia Wossnessctibkii Midd., Alaska. 



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



36. PladphoreUa vclata Cpr., California: a, minor lateral from inner side. 



37. Katlierina tunicaia Wood, Alaska. 



38. Acanthochiton aiicula Cpr., California. 



39. Acanthochiton spiculo8U8 Rye., "WeHt Indies. 



40. Macandrellm (coetatiis ? Ad. & Angas), Australia. 



Pl^TE V. 



41. Cnjptoconchus monticularis Quoy, New Zealand. 



42. Amicula FallasU Midd., Alaska. 



43. Anmula vesiitu Sow eihy, Massachusetts Bay. (Em^rsonu Couth.) 



44. Cryptochiion Slelleri Midd. , Alaska. 



45. Chitonellus fasdaius Quoy, Gaspar Straits: a, minor lateral from outer side. 



46. Viewof the anterior end of a Chiton from below: a, muzzle; &, 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 dno'eus Lowe (T. viarginatus Jeflfreys), 



after Loveu: a, embryo, in the egg; i, 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; c, 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 tlie form of the individual teeth rather than the superficial 

 appearance of the undisturbed raduhi. While the photographic relief 

 process, by which these plates were obtained fi'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 aitistic 

 modifications of a professional di'aughtsman unacquainted with the sub- 

 ject. 



