168 
Anterior Valve.—Three sharply-defined riblets. Covered 
with rounded or oblong pustules larger at the margin and 
decreasing in size towards the apex. Interior pearly. Inser- 
tion plates deep, three slits. 
Median Valve.—Dorsal area, wedge-shaped, foliated, 
covered with microscopic triangular pustules. Alternate 
black and white spots separate the dorsal from the pleural 
areas. lLatero-pleural area, covered with irregular rounded 
and elliptical tubercles, small near the dorsal area, growing 
much larger as they approach the girdle and the posterior 
edge. Sinus broad, insertion plates deep, one slit on each 
side. 
Posterior Valve.—Diminutive, mucro median, a distinct 
dorsal area similar to the median valves with irregular pus- 
tules below the mucro. Five microscopic riblets run from 
the mucro to the eaves. The dorsal area is concave. Articu- 
lamentum, bluish-green, rounded, excavated, deep insertion 
plates, two slits. 
Girdle.—Leathery, covered with spinelets. Five erect 
silvery tufts stand out prominently around the anterior valve 
and one tuft at each suture. The hollows in which these 
tufts are placed is surrounded by a prominent ridge. 
Hab.—Aldinga (by Mr. Kimber, after whom the shell is 
named), Kangaroo Island. 
Measurement.—Dried specimen, 10x 4 mm. 
Remarks.—1 have four specimens, varying somewhat 
in appearance, but similar in detail. 
60. Ischnochiton levis, sp. nov. Pl. vi, figs. SA -LAEY 
r 
General Appearance.—Smooth, rounded, decidedly ca 
inate, pale-cream colour with spots of yellow, very broad in 
proportion to length, valves narrow. 
Anterior Valve.—Smooth, except for a series of concen- 
tric growth-lines, microscopically granulated. 
Median Valve.—Regular growth-lines appear over the 
dorsal, lateral, and pleural areas. The lateral areas are 
slightly raised, the growth-lines making four very large fine 
longitudinal riblets. The pleural area is minutely reticulated. 
Posterior Valve.—Mucro ante-central. Two distinct 
areas, dorsal’and pleural, consisting of microscopic regular 
granulations. The rest of the valve is smooth, almost flat, 
with two or three concentric lines. Hight or nine irregutar 
slits, 
Girdle.—Coyered with rounded scales, microscopically 
striated. 
Measurement.—12 x 6 mm. 

