GASTEROPODA. 381 
vated, spirally nodding behind the centre. Within, porcelain-white 
and glistening; margin acute, everted; interior lamina the vertical 
half of an inverted cone, short, obliquely truncated, inclining back- 
wards. 
Length half an inch; breadth three-fifths of an inch; height one- 
fourth of an inch. 
Obtained at Porto Praya, Cape de Verde Islands. 
Allied to C. equestris. Its depressed, orbicular, and comparatively 
regular form, its short cup, and its colour, are its characteristics. 
Figures 487, 487 a, 487 6, back, base, and side of the shell; 487 c, 
details of sculpture, magnified ; 487 d, the cup. 
CaLYPTRHA RADIOSA (Gould). 
Testa trregularis, tenuis, alba, lucida, ad basim rotundata, obliqueé 
globoso-conica, lineis acutis numerosis elevatis cum stris tenuissimis 
intercalarus radiata; apice postico, obtuso: lamella interna elongata, 
semi-volutata, per-oblique truncata ; basi atlenuato ; cornubus lanceo- 
latis. 
C. radiosa, Goutp ; Proceed. Boston Soc. Nat. Hist., ii. 161. Aug. 
1846. Expedition Shells, 15. 
SHELL irregular, the vertex elevated, somewhat posterior, obtuse ; 
base circular, and the form obliquely conical, semiglobose. It is pure 
white, shining, transparent; radiately marked with fine, sharp, raised 
lines, at a little distance from each other, and between each two of 
which are found from two to four (generally three) still finer lines. 
Interior white and shining. ‘The interior lamella is rolled into half a 
cone, attached very delicately at the vertex, and its free extremity is 
very obliquely truncated, so as to form two lanceolate horns. Along 
the back it is slightly gibbous. 
Diameter half an inch; altitude two-fifths of an inch. 
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