REPORT ON THE POLYPLACOPHORA. 15 



B. — IsCHNOIDEA. 



Callochiton, Gray. 

 Callochiton platessa (Gould). 



Chiton platessa, Gould, Proc. Boston Soc. Nat. Hist., 1846, vol. ii. p. 143; U.S. Explor. Exped., 

 (Wilkes), 1852, vol. xii. p. 320. 

 ,, crocinus, Reeve, Conch. Icon., 1847, pi. xxii. fig. 146. 

 Leptochiton versicolor, A. Adams, Proc. Zool. Soc. Lond., 1852, p. 92, pi. xvi. fig. 5. 

 Lepidopleura platessa, Gould, Otia (Rectifications), 1862, p. 242. 

 Leptochiton versicolor, Angas, Proc. Zool. Soc. Lond., 1867, p. 223. 



Habitat. — Port Jackson. 6 to 15 fathoms. 



Australia (Gould and British Museum) ; Botany Bay (Angas) ; New Zealand (British 

 Museum). 



The tablets in the British Museum testify to Carpenter's acceptance of the above 

 synonymy. 



Shell. — Smooth, entire surface delicately shagreened, terminal valves and lateral areas 

 only with indistinct concentric lines of growth ; lateral areas not prominent, with no 

 radial markings ; umbones small, pointed. 



Girdle. — With delicate flat elongated scales. 



Gills. — Extend along whole length of foot, about thirty in number on each side. 



Colour. — Central areas yellowish, obscurely mottled with orange ; on some valves there 

 are a central and a lateral pair of pale lines. Lateral areas and terminal valves of a 

 uniform dull orange colour, and uniformly spotted with minute black dots, which are 

 absent from the central areas, the posterior border of the valves is ornamented with 

 alternate lighter and darker spots. Ligament brownish, with a few irregular small white 

 flecks and five large white spots, four very large spots extending from the points of 

 junction of the first and second, and seventh and eighth valves respectively, to the edge 

 of the girdle ; the fifth spot being in the median line posteriorly. 



Adams' description agrees, on the whole, very well with the single specimen collected 

 by the Expedition, but the coloration of his figure is not at all similar, with the excep- 

 tion of the very characteristic five white spots on the girdle. 



Angas describes his specimens as being variegated with maroon and olive. 



Isclmochiton, s.s. Carpenter. 

 Ischnochiton boogii, n.n. 



Cliiton roseus, Sowerby (not of Blainville), Proc. Zool. Soc. Lond., 1832, p. 58; Conch. Hlustr., 1841, 

 p. 5, No. 59, pi. xxxix. fig. 14. 

 „ „ Reeve, Conch. Icon., 1847, pL xxv. fig. 119. 



Habitat. — Station 113a. September 2, 1873. Fernando-Noronha anchorage. 7 to 

 25 fathoms. 



