ISCHNOCHITON. 55 



Subgenus VII. ISCHNORADSIA Shuttlew. 



Shell oval, as in Ischnochiton ; girdle covered with solid, convex, 

 smooth scales, like those of Chiton s. s. 



Section Ischnoradsia s. s. Median valves having several side 

 slits. Type J. australis Sowb. 



Section Lepidozona Pils. Median valves having one side slit. 

 Type I. mertensii Midd. 



Subgenus I. STENOCHITON Adams and Angas, 1864. 



Stenochiton AD. AND ANG., P. Z. S. 1864, p. 193. 



Shell very much elongated, roundly arched ; valves Ischnoid, 

 the central valves having several slits ; girdle having minute smooth 

 imbricating scales. 



This section was discarded by Carpenter, who referred its only 

 species to his own later group Stenoradsia with doubt ; Stenochiton, 

 however, seems to have as much individuality as most of the divis- 

 ions of Ischnochiton, and may be allowed to stand as a subgenus. 



I. JULOIDES Adams and Angas. PL 16, figs. 6, 7, 8. 



Shell much elongated, narrow, narrower in front; rufous brown, 

 minutely spotted with white. Valves narrow, longer than wide, 

 very convex, not carinated; lateral margins scarcely rounded, pol- 

 ished. Lateral areas elevated and at the margins concentrically 

 sulcate. Girdle narrow, pale-brown, spotted with black-brown, 

 covered with very minute, polished, imbricating scales. (Ad. and 

 Ang.) Length 25, breadth 6 mill. 



Holdfast Bay, South Australia. 



Stenochiton juloides AD. AND ANG., P. Z. S. 1864, p. ?93; 1. c. 

 1865, p. 58, t. 11, f. 15. ANGAS, P. Z. S. 1865, p. 188. "J Stenor- 

 adsia " juloides Ad. and Ang., CPU. MS. 



This species, from its narrow, convex form and polished surface 

 has much the general appearance of a Myriapod. (Ad. and Ang.) 



This species is the type of the genus Stenochiton Adams and 

 Angas, which is thus characterized by them : " Shell elongated, 

 narrow, convex ; valves longer than wide, not carinated ; apex of 

 the posterior valve subcentral ; plates of insertion small, multi- 

 fissate in the end valves, the intermediate valves having 5 fissures 

 on each side ; girdle covered with very minute, polished, imbrica- 

 ting scales." 



