REPORT ON THE POLYPLACOPHORA. 35 



Intermediate valves. — Central area: smooth, with fine lines of growth; no distinct 

 keel. Lateral areas : prominent, concentrically rugose, with a beaded ridge along the 

 anterior border, and, to a less extent, along the posterior border. Under surface with a 

 median horizontal rib-like swelling ; sutural laminae broad, but not deep ; jugal sinus 

 shallow ; one lateral slit ; eaves short. 



Posterior valve. — Anterior area so large as to reduce the posterior area to a minimum ; 

 smooth ; umbo minute, nearly terminal. Posterior area merely forms a concentrically 

 grooved thickening of the posterior border of the valve. Under surface : sutural laminaa 

 as before, but the jugal sinus is comparatively narrow and deep ; slits and teeth absent ; 

 the posterior border is greatly swollen. 



Girdle. — Closely beset with very minute horny spines. The specimen had been dried 

 when I received it, and none of the longer spines, characteristic of other species, are observ- 

 able ; but I think I can discern traces of small sutural tufts. 



Colour. — Anterior valve : a median triangular area, with the apex at the umbo, is of a 

 kind of chocolate colour, which is variegated with minute zigzag grey lines ; the lateral 

 spaces are of a dark slate colour. 



Intermediate valves. — Central area: Jugum pink; greenish towards the umbo when 

 worn down. Pleura dark greenish brown, with irregular longitudinal green bands. Lateral 

 areas : madder brown, blotched with brown. 



Posterior valve. — Anterior area resembling the central areas ; posterior border pinkish. 



Under surface of all the valves pale bluish green ; laminae of insertion white. 



Girdle. — Reddish brown. 



Size. — Length, 14 mm. ; breadth, 9 mm. ; height, 4 mm. 



This species, which is the handsomest of the genus, is dedicated to the memory of Dr 

 P. P. Carpenter, whose great knowledge of the group is fully acknowledged by all those 

 who work after him. 



The sculpture of the shell, slight as it is, is sufficient to characterise this species. 



G.— Mopaloidea. 

 Genus Acanthochiton (Leach), Herrmannsen. 



Acanthochiton garnoti (Blainville). 



Cliiton garnoti, Blainville, Diet, des Sci. Nat., 1825, vol. xxxvi. p. 552. 



„ „ Quoy and Gaimard, Voyage de l'Astrolabe, 1834, vol. iii. p. 401, pL lxxiii. figs. 9-14. 



„ danielli, Sowerby, Conch. Illust., 1841, p. 7, No. 91, pL xliv. fig. 48. 



Habitat.— Sea, Point, near Cape Town. Shore. Seven specimens. 

 Sowerby (loc cit., p. 7) erroneously gives Peru as the locality of Acanthochiton garnoti. 

 He says: " C. hirudiniformis, Sow., Zool. Proc, 1832, p. 59, Con. Illus., f. 23, 48, 142, 



