UMBRACULUM. 183 
is radiated, the rays being thickened and coarsely scaly. When 
the epidermis is removed the shell is a beautiful white, and shows 
ten obtuse angles which radiate from the center toward the periph- 
ery, but which are placed at unequal intervals and completely dis- 
appear before they reach the circumference. The edges of the 
shell are thin and sharp. Below in the middle there is a large dis- 
coidal area, sometimes of a brownish fawn, sometimes of a paler tint, 
verging toward orange. This spot is proportionally smaller than 
in the U. indica, and moreover, is nearly smooth, not showing the 
deep radial incisions which characterize that species. In U. eum- 
ingi this area is definitely bounded by a narrow white zone with 
irregular contours, representing the muscle impression. Below 
this impression may be remarked a rather narrow zone, washed 
with pale fawn; and finally, the rest of the shell is a very pure 
milk-white. In the smaller and younger individual figured, the 
shell is transparent enough to show through some of the epi- 
dermal rays. 
Description and figures from Deshayes. The smooth central 
area seems to be its most prominent feature. 
U. pictum A. Adams. 
Shell orbiculate-oval, flat, the apex produced, brown, incurved ; 
covered with a thin corneous epidermis, concentrically striated, 
whitish, radially painted with orange; interior shining, orange at 
the margin. (Ad.). 
Lord Hood's Island (Mus. Hasler). 
Operculatum pictum A. Av., P. Z.8., 1854, p. 187. 
This species is richly painted with reddish-orange, disposed in a 
radiated manner around the outer margin, the rays extending 
towards the center; the apex is hooked and more elevated than in 
the other species. (Ad.). 
U. corticaALis Tate. Pl. 70, fig. 62. 
Shell orbicular in outline, moderately elevated, with the apex 
prominent, somewhat incurved, and a little excentric; covered 
except apex, with a well developed epidermis, which extends about 
half as far again as the shell. The epidermis is raised into about 20 
broad rays, diverging from the apex, and is concentrically lamellose. 
It is pellucid white, but encircled with a band of maroon color, 
corresponding with the edge of the shell; it is very tough, and can 


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