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. cum- 

 in <l I 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. AD., P. Z. S., 1854, p. 137. 



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. CORTICALIS Tate. PI. 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 

 be readily removed in one piece. 



