100 ISCHNOCHITON. 



Var. punctulata. Shell carinated, ashen-whitish, unicolored or 

 spotted and dotted with brown ; very finely punctate. Lateral 

 areas and end valves radially striated. Length 22, breadth 10 

 mill. The valves are keeled and covered with regularly arranged 

 elevated points only to be seen under a lens. 



As an illustration of this variety Krauss refers to Sowerby's 

 Conchol. Illustr. fig. 55, but in my opinion this is not correct. 



I. ONISCUS Krauss. PI. 20, figs. 12, 3, 14, 15. 



Shell small, ovate-oblong, thin, semipellucid, subcarinated ; white, 

 rarely with a reddish dorsal band, or yellowish with green dots. 



Intermediate valves having the central areas very finely punctu- 

 late in the middle and longitudinally striolate at the sides ; lateral 

 areas and end valves finely undulately striolate. Girdle yellowish, 

 maculated with green, scaly, the scales very minute, oblong, smooth. 

 (Krauss.) Length 10, width 5'6 mill. 



Natal, on the shore. 



Chiton oniscus KR., Die Siidafric. Moll. p. 39, t. 3, f. 4. Ischno- 

 chiton oniscus CPR., MS. 



This species, whilst it has a superficial resemblance to /. textilis 

 Gray, is readily distinguished under the lens by the smaller and 

 smooth scales and by the smaller number of slits. The valves as 

 well as the girdle appear smooth to the naked eye, but the lateral 

 areas are visible. Under the lens the central areas are very finely 

 punctate on the dorsum, and on the pleura they are longitudinally 

 striated ; these striae continue upon the lateral areas becoming wavy 

 strise there. The end valves have feeble wavy strise toward the 

 margins, and have 10 slits in their insertion plates. The interme- 

 diate valves are strongly convex, 5 mill, wide, 4 long, rounded at 

 both sides, and having a single slit in each insertion plate. One 

 specimen is white with greenish-brown girdle ; another is whitish 

 with a red-brown band along the back ; a third specimen is dirty 

 yellow with green dots, the girdle also green dotted. (Krauss. ") 



Carpenter gives this note on specimens received by him from 

 Stimpson : Terminal valves having 10-12, central 1 slit: teeth 

 acute ; eaves short, spongy ; sinus broad, flat. In one of the speci- 

 mens examined the hind valve has the central teeth very small and 

 clos*, while the side teeth are long and distant. 



