BEDJJ-ALL : SOUTH ATJSTKALIAiS' POLTPLACOPHOEA. 



147 



The distinct granular ornamentation of this species at once dis- 

 tingaiishes it from any other South Australian Chiton. It is curious, 

 therefore, that Mr. Angas, who collected it in this Colony, did not 

 recognize its identity with the shells in the Cumingian Collection, 

 described by Eeeve as under the above name. 



13. IscHNOCHiTON- PTYCHius, Pilsbry. 

 Ischnochiton ptychius, Pilsbry: Nautilus, vol. viii, p. 53. 



It is a small oval pink-tinged shell, with wrinkled striations on the 

 dorsal areas, and somewhat coarse concentric sulcations on the lateral 

 areas, which are strongly serrated at the sutural margin. Length 1 1 , 

 breadth 8 mm. 



Hah. — One specimen, St. Vincent's Gulf, in all probability at Port 

 Willunga (Bednall). A second one has been obtained by Mr. E. H. 

 Matthews at Sultana Kay. 



14. IscHNocHiToisr Tateanus, n.sp. PI. XII, Fig. 3. 



Shell oval, elevated, obtusely carinated, side slopes slightly convex ; 

 colour generally of a sordid grey, minutely mottled with brown or 

 green, sometimes spotted with brown ; in occasional specimens the 

 second, thii'd, and sixth valves are black. Interior whitish, tinged 

 with purjile green, yellow, or brown in 

 different examples. Central valves finely 

 decussated throughoiit, not excepting the 

 summits, with veiy fine, even pustulose, 

 striations, becoming a little coarser and more 

 defined on the side slopes towards the 

 margin ; lateral areas somewhat raised, and 

 having about five to seven somewhat in- 

 distinct, roughened riblets, the riblet on the 

 posterior edge being double the width of 

 the others, and cut up into transverse, back- 

 wardly diverging, short riblets or oblong 

 pustules by concentric grooves, which strongly 

 sen-ate the posterior edge of the valve. In 

 some specimens the growth-lines are strongly 

 marked. Anterior valve with numerous 

 thread-like pustulose stria3, j)osterior edge 

 serrated similarly to the central valves. 

 The tail valve having the mucro central, and 



the posterior sharply defined from the central Ischnochiton Tateamis, n.sp. 

 area. The fonner ornamented with riblets 



radiating as in the anterior valve ; the central area being sculptured 

 like the immediately preceding valve, the slope from the umbo is 

 concave. Sinus very wide and shallow. Anterior valve 9 or 10, 

 central 1, posterior 8 slits. Girdle naiTow, composed of scales deeply 

 grooved on the outer edge, very closely and in-egularly set together, 

 gradually diminishing in size towards the outer edge. Length 21, 

 breadth 1 2 mm. 



