136 ISCHNOCHITOX. 



usually with three main radiating low ridges, the anterior and pos- 

 terior of which are often bifid. Posterior valve concentrically 

 rugose, with fifteen irregularly arranged low radiating ridges. The 

 anterior ridge is broader than the others, and may be slightly bifid, 

 umbo rudimentary ; anterior border smooth, with slight concentric 

 lines of growth. Laminae of insertion moderate in size. 



Girdle narrow. Upper surface with ovoid, slightly overlapping, 

 somewhat granular scales ; edge with minute projecting spicules ; 

 under surface, with long, narrow, closely applied scales. Color 

 white. 



Length 21'5, breadth 7'5, height 6 mill. (Haddon.) 



Prince Edward's Island, Lat. 46 41' S., long. 38 10' W. 310 

 fms. 



Lepidopleurus dorsuosus HADDON, Challenger Polyplac., p. 18, t. 

 1, f. 5; t. 3, f. 5a-5i. 1886. 



Gills extending to more than half the length of the foot, twenty in 

 number, the middle somewhat larger than the remainder. The 

 name dorsuosus, full of ridges, is applicable to this species on 

 account of its numerous longitudinal and radiating ridges, and at the 

 same time recalling the steep ridge of the shell itself. (Haddon.) 



I. ADELAIDENSIS Reeve. PL 24, figs. 7, 8 (enlarged.) 



Shell somewhat shortly ovate, very minutely reticulated through- 

 out, under the lens ; terminal valves and lateral areas of the rest 

 finely ridged, ridges waved, central areas smooth, lateral areas not 

 raised; livid olive and yellow, flamed with brown in the middle, 

 posterior edges of the valves articulated with brown ; ligament 

 granately coriaceous, grains very large. (Rve.) 



Port Adelaide (Rve.) ; Port Nolle, Queensland (Coppinger), Aus- 

 tralia. 



Chiton adelaidensis REEVE, Conch. Icon., t, 19, f. 123. C. (Isch- 

 nochiton /) adelaidensis E. A. SMITH, Zool. H. M. S. ' Alert,' p. 

 79, 1884. Lepidopleurus adelaidensis CPU., MS. 



Smith gives the following notes on the specimens collected at 

 Port Molle by Coppinger : 



The entire surface of this species is minutely granosely reticulated, 

 the front valve, the lateral areas of the narrow central valves, and 

 the hinder area of the posterior are in addition somewhat irregularly 

 radiately sulcate. The prevailing color is pale greenish, streaked 

 and dotted with red, the posterior margin of the valves being paler 



