8 _ 
by numerous conspicuous close-set bead-like nodules ; inter- 
stices somewhat wider than the ribs, concave, crossed by 
irregular concentric strize or growth lines. Umbones situated 
on the anterior side, sharp at the apex, and incurved. Posterior 
dorsal margin convex slightly sloping; anterior truncate ; 
ventral and lateral margins rounded. Posterior cardinal area 
narrow and concave; ligament rather short; anterior lunule 
rather narrow. very slightly depressed. Interior white, faintly 
radiately grooved; margin denticulated ; posterior abductor 
scar irregular, subtrigonal, striated ; anterior oblong-ovate ; 
pallial line distinct, simple. Hinge rather thick, right valve 
furnished with two cardinal teeth, the posterior one thick and 
obliquely triangular, the anterior very small and diverging ; 
left valve with one solid rounded tooth; in each valve the 
posterior cardinal lamina is rather long, terminating in a slightly 
raised rounded lateral tooth ; anterior lamina shorter, with a 
slight thickening at the end scarcely to be called a tooth. 
Measurement :—Umbones to ventral margin, 10; anterior 
to posterior, 9} ; thickness (valves united), 7 millim. 
Hab. :—Cape Natal, W. by N., 64 miles; depth, 54 fathoms. 
A very pretty little shell, in w hich the numerous prominent 
ribs have the appearance of chains of beads. In form it 
resembles C. cardioides, Reeve. 
Fam. Crassatellide. 
CRASSATELLA GILCHRISTI, n. sp. (Plate VI., fig. 14). Shell 
transversely oblong, rather solid, somewhat compressed, very 
obtusely angled posteriorly ; surface very finely decussated 
throughout with concentric and radiating striz ; concentrically 
ridged with rather broad, slightly-raised lire, about equal in 
width to the interstices, becoming obsolete at each end; 
covered with a thin brown periostracum. Posterior dorsal 
margin rather straight, sloping, terminating in a very obtuse, 
rounded angle ; anterior truncated, rather convex ; posterior 
lateral margin sloping, very slightly convex, anterior 
rounded ; ventral margin rather straight, obliquely rounded 
at the anterior end, and roundly angled at the posterior. 
Umbones minute, scarcely curved; posterior cardinal area 
rather short, impressed, slightly concave; anterior lunule 
rather long and narrow. Interior white, margin serrated ; 
anterior abductor scar rather large, irregularly oblong-oval ; 
posterior short, angular in front, rounded behind ; anterior 
pedal retractor small, sunken; pallial line simple. Hinge 
